chore(release): 5.1.0 [skip ci]

Fixes #7

.clang-format

@@ -1,2 +1,2 @@
-BasedOnStyle: 'Google'
+BasedOnStyle: "Google"
 ColumnLimit: 0

.github/ISSUE_TEMPLATE/BUG.md

@@ -1,8 +1,8 @@
 ---
-name: '🐛 Bug Report'
+name: "🐛 Bug Report"
-about: 'Report an unexpected problem or unintended behavior.'
+about: "Report an unexpected problem or unintended behavior."
-title: '[Bug]'
+title: "[Bug]"
-labels: 'bug'
+labels: "bug"
 ---
 
 <!--

.github/ISSUE_TEMPLATE/DOCUMENTATION.md

@@ -1,8 +1,8 @@
 ---
-name: '📜 Documentation'
+name: "📜 Documentation"
-about: 'Correct spelling errors, improvements or additions to documentation files (README, CONTRIBUTING...).'
+about: "Correct spelling errors, improvements or additions to documentation files (README, CONTRIBUTING...)."
-title: '[Documentation]'
+title: "[Documentation]"
-labels: 'documentation'
+labels: "documentation"
 ---
 
 <!-- Please make sure your issue has not already been fixed. -->

.github/ISSUE_TEMPLATE/FEATURE_REQUEST.md

@@ -1,8 +1,8 @@
 ---
-name: '✨ Feature Request'
+name: "✨ Feature Request"
-about: 'Suggest a new feature idea.'
+about: "Suggest a new feature idea."
-title: '[Feature]'
+title: "[Feature]"
-labels: 'feature request'
+labels: "feature request"
 ---
 
 <!-- Please make sure your issue has not already been fixed. -->

.github/ISSUE_TEMPLATE/IMPROVEMENT.md

@@ -1,8 +1,8 @@
 ---
-name: '🔧 Improvement'
+name: "🔧 Improvement"
-about: 'Improve structure/format/performance/refactor/tests of the code.'
+about: "Improve structure/format/performance/refactor/tests of the code."
-title: '[Improvement]'
+title: "[Improvement]"
-labels: 'improvement'
+labels: "improvement"
 ---
 
 <!-- Please make sure your issue has not already been fixed. -->

.github/ISSUE_TEMPLATE/QUESTION.md

@@ -1,8 +1,8 @@
 ---
-name: '🙋 Question'
+name: "🙋 Question"
-about: 'Further information is requested.'
+about: "Further information is requested."
-title: '[Question]'
+title: "[Question]"
-labels: 'question'
+labels: "question"
 ---
 
 ### Question

.github/workflows/ci.yml

@@ -1,40 +1,40 @@
-name: 'CI'
+name: "CI"
 
 on:
   push:
     branches: [develop]
   pull_request:
-    branches: [master, develop]
+    branches: [main, develop]
 
 jobs:
   ci:
-    runs-on: 'ubuntu-latest'
+    runs-on: "ubuntu-latest"
     steps:
-      - uses: 'actions/checkout@v3.5.3'
+      - uses: "actions/checkout@v4.1.7"
 
-      - run: 'sudo apt update'
+      - run: "sudo apt update"
 
-      - name: 'Install Build Tools'
+      - name: "Install Build Tools"
-        run: 'sudo apt-get install --yes build-essential gcc make clang-format'
+        run: "sudo apt install --yes build-essential gcc make clang-format"
 
-      - name: 'Install Documentation Tools'
+      - name: "Install Documentation Tools"
-        run: 'sudo apt-get install --yes doxygen doxygen-gui doxygen-doc graphviz'
+        run: "sudo apt install --yes doxygen doxygen-gui doxygen-doc graphviz"
 
-      - run: 'gcc --version'
+      - run: "gcc --version"
 
-      - run: 'make'
+      - run: "make"
-      - run: 'make run'
+      - run: "make run"
-      - run: 'make test'
+      - run: "make test"
-      - run: 'make lint'
+      - run: "make lint"
-      - run: 'make documentation'
+      - run: "make documentation"
-      - run: 'make set_version'
+      - run: "make set_version"
-      - run: 'make clean'
+      - run: "make clean"
 
   lint-commit:
-      runs-on: 'ubuntu-latest'
+    runs-on: "ubuntu-latest"
-      steps:
+    steps:
-        - uses: 'actions/checkout@v3.5.3'
+      - uses: "actions/checkout@v4.1.7"
-          with:
+        with:
-            fetch-depth: 0
+          fetch-depth: 0
 
-        - uses: 'wagoid/commitlint-github-action@v5.4.1'
+      - uses: "wagoid/commitlint-github-action@v6.1.2"

.github/workflows/release.yml

@@ -1,57 +1,57 @@
-name: 'Release'
+name: "Release"
 
 on:
   push:
-    branches: [master]
+    branches: [main]
 
 jobs:
   release:
-    runs-on: 'ubuntu-latest'
+    runs-on: "ubuntu-latest"
     steps:
-      - uses: 'actions/checkout@v3.5.3'
+      - uses: "actions/checkout@v4.1.7"
         with:
           fetch-depth: 0
           persist-credentials: false
-          submodules: recursive
+          submodules: "recursive"
 
-      - name: 'Import GPG key'
+      - name: "Import GPG key"
-        uses: 'crazy-max/ghaction-import-gpg@v5.3.0'
+        uses: "crazy-max/ghaction-import-gpg@v6.1.0"
         with:
           gpg_private_key: ${{ secrets.GPG_PRIVATE_KEY }}
           git_user_signingkey: true
           git_commit_gpgsign: true
 
-      - run: 'sudo apt update'
+      - run: "sudo apt update"
 
-      - name: 'Install Build Tools'
+      - name: "Install Build Tools"
-        run: 'sudo apt-get install --yes build-essential gcc make clang-format'
+        run: "sudo apt install --yes build-essential gcc make clang-format"
 
-      - name: 'Install Documentation Tools'
+      - name: "Install Documentation Tools"
-        run: 'sudo apt-get install --yes doxygen doxygen-gui doxygen-doc graphviz'
+        run: "sudo apt install --yes doxygen doxygen-gui doxygen-doc graphviz"
 
-      - run: 'make set_version'
+      - run: "make set_version"
 
-      - name: 'Use Node.js'
+      - name: "Use Node.js"
-        uses: 'actions/setup-node@v3.7.0'
+        uses: "actions/setup-node@v4.0.3"
         with:
-          node-version: '18.17.0'
+          node-version: "20.17.0"
 
-      - name: 'Install Release Tools'
+      - name: "Install Release Tools"
-        run: 'npm install --save-dev semantic-release@21.0.7 @commitlint/cli@17.6.7 @commitlint/config-conventional@17.6.7 @semantic-release/git@10.0.1 @semantic-release/exec@6.0.3 @saithodev/semantic-release-backmerge@3.2.0 vercel@31.2.2'
+        run: "npm install --save-dev semantic-release@23.1.1 @commitlint/cli@19.5.0 @commitlint/config-conventional@19.5.0 @semantic-release/git@10.0.1 @semantic-release/exec@6.0.3 @saithodev/semantic-release-backmerge@4.0.1 vercel@37.4.2"
 
-      - run: 'rm --force package.json package-lock.json'
+      - run: "rm --force package.json package-lock.json"
 
-      - name: 'Release'
+      - name: "Release"
-        run: 'npx semantic-release'
+        run: "npx semantic-release"
         env:
           GH_TOKEN: ${{ secrets.GH_TOKEN }}
           GIT_COMMITTER_NAME: ${{ secrets.GIT_NAME }}
           GIT_COMMITTER_EMAIL: ${{ secrets.GIT_EMAIL }}
 
-      - name: 'Generate Documentation'
+      - name: "Generate Documentation"
-        run: 'make documentation'
+        run: "make documentation"
 
-      - name: 'Deploy to Vercel'
+      - name: "Deploy to Vercel"
         run: 'npx vercel ./documentation/html --token="${VERCEL_TOKEN}" --prod'
         env:
           VERCEL_TOKEN: ${{ secrets.VERCEL_TOKEN }}

.releaserc.json

@@ -1,5 +1,5 @@
 {
-  "branches": ["master"],
+  "branches": ["main"],
   "plugins": [
     [
       "@semantic-release/commit-analyzer",
@@ -30,7 +30,7 @@
     [
       "@saithodev/semantic-release-backmerge",
       {
-        "branches": [{ "from": "master", "to": "develop" }],
+        "branches": [{ "from": "main", "to": "develop" }],
         "backmergeStrategy": "merge"
       }
     ]

CONTRIBUTING.md

@@ -30,3 +30,18 @@ If you're adding new features to **libcproject**, please include tests.
 ## Commits
 
 The commit message guidelines adheres to [Conventional Commits](https://www.conventionalcommits.org/) and [Semantic Versioning](https://semver.org/) for releases.
+
+## Git Submodules
+
+To get the submodule:
+
+```sh
+git submodule update --init --recursive
+```
+
+To update the version:
+
+```sh
+cd doxygen-awesome-css
+git checkout v2.3.3
+```

Doxyfile

@@ -12,7 +12,7 @@ FILE_PATTERNS = *.h \
   CODE_OF_CONDUCT.md \
   CONTRIBUTING.md \
   LICENSE
-HTML_EXTRA_STYLESHEET  = doxygen-awesome-css/doxygen-awesome.css
+HTML_EXTRA_STYLESHEET = doxygen-awesome-css/doxygen-awesome.css
 
 RECURSIVE = YES
 EXCLUDE = test doxygen-awesome-css node_modules

LICENSE

@@ -1,6 +1,6 @@
-MIT License
+# MIT License
 
-Copyright (c) Théo LUDWIG
+Copyright (c) Théo LUDWIG <contact@theoludwig.fr>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Makefile

@@ -32,13 +32,13 @@ build/test/%.o: test/%.c ${HEADER_FILES} | build/test
 .PHONY: run
 run: ${LIB} ./main.c
 	mkdir --parents ./bin
-	${CC} ${CC_FLAGS} -o ${MAIN_EXECUTABLE} ./main.c ${LIB_CC_FLAGS}
+	${CC} ${CC_FLAGS} ${CC_SANITIZER_FLAGS} -o ${MAIN_EXECUTABLE} ./main.c ${LIB_CC_FLAGS}
 	./${MAIN_EXECUTABLE} ${ARGS}
 
 .PHONY: set_version
 set_version: ${LIB} ./set_version.c
 	mkdir --parents ./bin
-	${CC} ${CC_FLAGS} -o ${SET_VERSION_EXECUTABLE} ./set_version.c ${LIB_CC_FLAGS}
+	${CC} ${CC_FLAGS} ${CC_SANITIZER_FLAGS} -o ${SET_VERSION_EXECUTABLE} ./set_version.c ${LIB_CC_FLAGS}
 
 .PHONY: test
 test: ${LIB} $(addprefix build/, ${TEST_OBJECTS})

README.md

@@ -5,11 +5,11 @@
 </p>
 
 <p align="center">
-  <a href="./CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat" /></a>
+  <a href="./CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat" alt="Contributing" /></a>
   <a href="./LICENSE"><img src="https://img.shields.io/badge/licence-MIT-blue.svg" alt="Licence MIT"/></a>
   <a href="./CODE_OF_CONDUCT.md"><img src="https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg" alt="Contributor Covenant" /></a>
   <br />
-  <a href="https://github.com/theoludwig/libcproject/actions/workflows/ci.yml"><img src="https://github.com/theoludwig/libcproject/actions/workflows/ci.yml/badge.svg?branch=develop" /></a>
+  <a href="https://github.com/theoludwig/libcproject/actions/workflows/ci.yml"><img src="https://github.com/theoludwig/libcproject/actions/workflows/ci.yml/badge.svg?branch=develop" alt="CI" /></a>
   <a href="https://conventionalcommits.org"><img src="https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg" alt="Conventional Commits" /></a>
   <a href="https://github.com/semantic-release/semantic-release"><img src="https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg" alt="semantic-release" /></a>
 </p>
@@ -37,10 +37,10 @@ For example on GNU/Linux Ubuntu:
 
 ```sh
 # Install Build Tools
-sudo apt-get install build-essential gcc make clang-format
+sudo apt install build-essential gcc make clang-format
 
 # Install Documentation Tools
-sudo apt-get install doxygen doxygen-gui doxygen-doc graphviz
+sudo apt install doxygen doxygen-gui doxygen-doc graphviz
 ```
 
 ## Usage
@@ -92,9 +92,9 @@ touch main.c
 #include "libcproject/libcproject.h"
 
 int main() {
-  string_t string_value = "Hello, world!"; // `string_t` is a typedef from `libcproject`
+  string_t string = "Hello, world!"; // `string_t` is a typedef from `libcproject`
-  printf("%s\n", string_value);
+  printf("%s\n", string);
-  printf("string_length = %ld\n", string_get_length(string_value)); // `string_get_length` is a function from `libcproject`
+  printf("string_length = %ld\n", string_get_length(string)); // `string_get_length` is a function from `libcproject`
   return EXIT_SUCCESS;
 }
 ```

doxygen-awesome-css

@@ -1 +1 @@
-Subproject commit df83fbf22cfff76b875c13d324baf584c74e96d0
+Subproject commit 40e9b25b6174dd3b472d8868f63323a870dfeeb8

lib/array_list.c

@@ -1,18 +1,35 @@
 #include "array_list.h"
 
 struct array_list* array_list_initialization() {
+  return array_list_initialization_with_capacity(ARRAY_LIST_INITIAL_CAPACITY);
+}
+
+struct array_list* array_list_initialization_with_capacity(size_t capacity) {
   struct array_list* list = malloc(sizeof(struct array_list));
-  list->data = malloc(sizeof(void*) * ARRAY_LIST_INITIAL_CAPACITY);
+  if (list == NULL) {
+    perror("Error (array_list_initialization)");
+    exit(EXIT_FAILURE);
+  }
   list->size = 0;
-  list->capacity = ARRAY_LIST_INITIAL_CAPACITY;
+  list->capacity = capacity;
+  list->capacity_step = capacity;
+  list->data = malloc(sizeof(void*) * list->capacity);
+  if (list->data == NULL) {
+    perror("Error (array_list_initialization)");
+    exit(EXIT_FAILURE);
+  }
   return list;
 }
 
 void array_list_add(struct array_list* list, void* element) {
   if (list->size >= list->capacity) {
     size_t previous_capacity = list->capacity;
-    list->capacity += ARRAY_LIST_INITIAL_CAPACITY;
+    list->capacity += list->capacity_step;
     list->data = realloc(list->data, sizeof(void*) * list->capacity);
+    if (list->data == NULL) {
+      perror("Error (array_list_add)");
+      exit(EXIT_FAILURE);
+    }
     for (size_t index = previous_capacity; index < list->capacity; index++) {
       list->data[index] = NULL;
     }
@@ -25,8 +42,8 @@ void array_list_remove(struct array_list* list, size_t index) {
   if (index >= list->size) {
     return;
   }
-  for (size_t i = index + 1; i < list->size - 1; i++) {
+  for (size_t i = index; i < list->size - 1; i++) {
-    list->data[i - 1] = list->data[i];
+    list->data[i] = list->data[i + 1];
   }
   list->size--;
 }

lib/array_list.h

@@ -1,7 +1,9 @@
 #ifndef __LIBCPROJECT_ARRAY_LIST__
 #define __LIBCPROJECT_ARRAY_LIST__
 
+#include <errno.h>
 #include <stdbool.h>
+#include <stdio.h>
 #include <stdlib.h>
 
 #include "types.h"
@@ -16,6 +18,7 @@ struct array_list {
   void** data;
   size_t size;
   size_t capacity;
+  size_t capacity_step;
 };
 
 /**
@@ -24,26 +27,44 @@ struct array_list {
  */
 struct array_list* array_list_initialization();
 
+/**
+ * @brief Initializes a new array list with a capacity.
+ * @since v5.0.0
+ */
+struct array_list* array_list_initialization_with_capacity(size_t capacity);
+
 /**
  * @brief Adds an element to the end of the array list.
+ *
+ * @param list
+ * @param element
  * @since v1.2.0
  */
 void array_list_add(struct array_list* list, void* element);
 
 /**
  * @brief Removes an element from the array list.
+ *
+ * @param list
+ * @param index
  * @since v1.2.0
  */
 void array_list_remove(struct array_list* list, size_t index);
 
 /**
  * @brief Gets an element from the array list.
+ *
+ * @param list
+ * @param index
+ * @return void*
  * @since v1.2.0
  */
 void* array_list_get(struct array_list* list, size_t index);
 
 /**
  * @brief Frees the array list.
+ *
+ * @param list
  * @since v3.0.0
  */
 void array_list_free(struct array_list* list);

lib/assert.c

@@ -1,7 +1,7 @@
-#include "test.h"
+#include "assert.h"
 
 bool assert_string_equal(const string_t actual, const string_t expected) {
-  if (strcmp(expected, actual) != 0) {
+  if (!string_equals(actual, expected)) {
     printf("FAIL: expected = \"%s\" ; actual = \"%s\"\n", expected, actual);
     return false;
   }
@@ -9,7 +9,7 @@ bool assert_string_equal(const string_t actual, const string_t expected) {
 }
 
 bool assert_string_not_equal(const string_t actual, const string_t expected) {
-  if (strcmp(expected, actual) == 0) {
+  if (string_equals(actual, expected)) {
     printf("FAIL: expected = \"%s\" ; actual = \"%s\"\n", expected, actual);
     return false;
   }

lib/assert.h

@@ -0,0 +1,30 @@
+#ifndef __LIBCPROJECT_ASSERT__
+#define __LIBCPROJECT_ASSERT__
+
+#include <assert.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "string.h"
+#include "types.h"
+
+/**
+ * @brief Check if the two strings are equal. If they are not equal, print the expected and actual strings.
+ *
+ * @param character
+ * @return bool
+ * @since v5.0.0
+ */
+bool assert_string_equal(const string_t actual, const string_t expected);
+
+/**
+ * @brief Check if the two strings are not equal. If they are equal, print the expected and actual strings.
+ *
+ * @param character
+ * @return bool
+ * @since v5.0.0
+ */
+bool assert_string_not_equal(const string_t actual, const string_t expected);
+
+#endif

lib/character.c

@@ -1,17 +1,17 @@
 #include "character.h"
 
-void character_append(string_t string_value, const char character) {
+void character_append(string_t string, const char character) {
-  size_t length = string_get_length(string_value);
+  size_t length = string_get_length(string);
-  character_append_at(string_value, character, length);
+  character_append_at(string, character, length);
 }
 
-void character_append_at(string_t string_value, const char character, const size_t index) {
+void character_append_at(string_t string, const char character, const size_t index) {
-  size_t length = string_get_length(string_value);
+  size_t length = string_get_length(string);
   for (size_t index_string = length; index_string > index; index_string--) {
-    string_value[index_string] = string_value[index_string - 1];
+    string[index_string] = string[index_string - 1];
   }
-  string_value[index] = character;
+  string[index] = character;
-  string_value[length + 1] = '\0';
+  string[length + 1] = '\0';
 }
 
 char character_to_upper(const char character) {
@@ -32,9 +32,9 @@ bool character_get_is_digit(const char character) {
   return character >= '0' && character <= '9';
 }
 
-unsigned char character_get_alphabet_position(const char character) {
+uint8_t character_get_alphabet_position(const char character) {
   const char letter = character_to_lower(character);
-  unsigned char position = 0;
+  uint8_t position = 0;
   if (letter >= 'a' && letter <= 'z') {
     position = (letter - 'a') + 1;
   }

lib/character.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_CHARACTER__
 #define __LIBCPROJECT_CHARACTER__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
@@ -11,21 +12,21 @@
  * @brief Append a character to a string, assuming string points to an array
  * with enough space.
  *
- * @param string_value
+ * @param string
  * @param character
  * @since v1.0.0
  */
-void character_append(string_t string_value, char character);
+void character_append(string_t string, char character);
 
 /**
  * @brief Append a character to a string at a specific index, assuming string points to an array with enough space.
  *
- * @param string_value
+ * @param string
  * @param character
  * @param index
  * @since v1.0.0
  */
-void character_append_at(string_t string_value, const char character, const size_t index);
+void character_append_at(string_t string, const char character, const size_t index);
 
 /**
  * @brief Converts the character to uppercase.
@@ -46,7 +47,8 @@ char character_to_lower(const char character);
 /**
  * @brief Check if the character is a digit ('0', '1', '2', '3', '4', '5', '6', '7, '8' or '9').
  *
- * @return true if the character is a digit, false otherwise
+ * @param character
+ * @return bool
  * @since v1.0.0
  */
 bool character_get_is_digit(const char character);
@@ -56,8 +58,9 @@ bool character_get_is_digit(const char character);
  * Return 0 if the character is not a letter.
  *
  * @param character
+ * @return uint8_t
  * @since v1.0.0
  */
-unsigned char character_get_alphabet_position(const char character);
+uint8_t character_get_alphabet_position(const char character);
 
 #endif

lib/convert.c

@@ -3,6 +3,7 @@
 string_t convert_character_to_string(const char character) {
   string_t string = malloc(sizeof(char) * 2);
   if (string == NULL) {
+    perror("Error (convert_character_to_string)");
     exit(EXIT_FAILURE);
   }
   string[0] = character;
@@ -18,23 +19,23 @@ char convert_digit_to_character(const char digit) {
   return digit + '0';
 }
 
-long long convert_string_to_number(const string_t string_value) {
+int64_t convert_string_to_number(const string_t string) {
-  bool is_negative = string_value[0] == '-';
+  bool is_negative = string[0] == '-';
-  long long integer = 0;
+  int64_t integer = 0;
-  size_t length = string_get_length(string_value);
+  size_t length = string_get_length(string);
   for (size_t index = is_negative ? 1 : 0; index < length; index++) {
-    integer = integer * 10 + convert_character_to_digit(string_value[index]);
+    integer = integer * 10 + convert_character_to_digit(string[index]);
   }
   return is_negative ? integer * -1 : integer;
 }
 
-string_t convert_number_to_string(const long long integer) {
+string_t convert_number_to_string(const int64_t integer) {
   if (integer == 0) {
     return convert_character_to_string('0');
   }
   bool is_negative = integer < 0;
   size_t length = 1;
-  long long current = mathematics_absolute_value(integer);
+  int64_t current = mathematics_absolute_value(integer);
   while (current != 0) {
     current = current / 10;
     length++;
@@ -42,40 +43,40 @@ string_t convert_number_to_string(const long long integer) {
   if (is_negative) {
     length++;
   }
-  string_t string_value = malloc(sizeof(char) * length);
+  string_t string = malloc(sizeof(char) * length);
-  if (string_value == NULL) {
+  if (string == NULL) {
+    perror("Error (convert_number_to_string)");
     exit(EXIT_FAILURE);
   }
   current = mathematics_absolute_value(integer);
   size_t index = 0;
   while (current != 0) {
-    string_value[index++] = convert_digit_to_character(current % 10);
+    string[index++] = convert_digit_to_character(current % 10);
     current = current / 10;
   }
   if (is_negative) {
-    string_value[index++] = '-';
+    string[index++] = '-';
   }
-  string_value[index] = '\0';
+  string[index] = '\0';
-  char* result = string_reverse(string_value);
+  string_reverse(string);
-  free(string_value);
+  return string;
-  return result;
 }
 
-string_t convert_number_from_base_10_to_base(unsigned long long number, unsigned int base) {
+string_t convert_number_from_base_10_to_base(uint64_t number, uint64_t base) {
   if (number == 0) {
     return "0";
   }
-  int remainders[64];
+  int64_t remainders[64];
-  int index = 0;
+  int64_t index = 0;
   while (number > 0) {
     remainders[index] = number % base;
     number = number / base;
     index++;
   }
   string_t result = malloc(sizeof(char) * (index + 1));
-  int index_result = 0;
+  int64_t index_result = 0;
-  for (int iteration = index - 1; iteration >= 0; iteration--) {
+  for (int64_t iteration = index - 1; iteration >= 0; iteration--) {
-    int remainder = remainders[iteration];
+    int64_t remainder = remainders[iteration];
     if (remainder >= 10) {
       result[index_result] = (char)((remainder - 10) + 'A');
     } else {
@@ -87,17 +88,17 @@ string_t convert_number_from_base_10_to_base(unsigned long long number, unsigned
   return result;
 }
 
-int convert_number_from_base_to_base_10(string_t number, unsigned int base) {
+uint64_t convert_number_from_base_to_base_10(string_t number, uint64_t base) {
-  int length = string_get_length(number);
+  size_t length = string_get_length(number);
-  int exponent = length - 1;
+  int64_t exponent = length - 1;
-  int result = 0;
+  uint64_t result = 0;
-  int index = 0;
+  int64_t index = 0;
   while (exponent >= 0) {
-    int current_number = (int)(number[index] - '0');
+    int64_t current_number = (int64_t)(number[index] - '0');
     if (current_number >= 10) {
-      current_number = (int)(number[index] - 'A') + 10;
+      current_number = (int64_t)(number[index] - 'A') + 10;
     } else {
-      current_number = (int)(number[index] - '0');
+      current_number = (int64_t)(number[index] - '0');
     }
     result = result + current_number * mathematics_pow(base, exponent);
     exponent--;
@@ -106,6 +107,6 @@ int convert_number_from_base_to_base_10(string_t number, unsigned int base) {
   return result;
 }
 
-string_t convert_number_from_base_to_another(string_t number, int base_from, int base_target) {
+string_t convert_number_from_base_to_another(string_t number, uint64_t base_from, uint64_t base_target) {
   return convert_number_from_base_10_to_base(convert_number_from_base_to_base_10(number, base_from), base_target);
 }

lib/convert.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_CONVERT__
 #define __LIBCPROJECT_CONVERT__
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -14,6 +15,7 @@
  * @brief Convert a character to a string.
  *
  * @param character
+ * @return string_t
  * @since v1.0.0
  */
 string_t convert_character_to_string(const char character);
@@ -22,6 +24,7 @@ string_t convert_character_to_string(const char character);
  * @brief Convert a character to a digit.
  *
  * @param character
+ * @return char
  * @since v1.0.0
  */
 char convert_character_to_digit(const char character);
@@ -30,6 +33,7 @@ char convert_character_to_digit(const char character);
  * @brief Convert a digit to a character.
  *
  * @param digit
+ * @return char
  * @since v1.0.0
  */
 char convert_digit_to_character(const char digit);
@@ -37,36 +41,40 @@ char convert_digit_to_character(const char digit);
 /**
  * @brief Convert a string to a number.
  *
- * @param string_value
+ * @param string
+ * @return int64_t
  * @since v1.0.0
  */
-long long convert_string_to_number(const string_t string_value);
+int64_t convert_string_to_number(const string_t string);
 
 /**
  * @brief Convert a number to a string.
  *
  * @param integer
+ * @return string_t
  * @since v1.0.0
  */
-string_t convert_number_to_string(const long long integer);
+string_t convert_number_to_string(const int64_t integer);
 
 /**
  * @brief Convert a number (base 10) to a string with a specific base.
  *
  * @param number
  * @param base
+ * @return string_t
  * @since v1.0.0
  */
-string_t convert_number_from_base_10_to_base(unsigned long long number, unsigned int base);
+string_t convert_number_from_base_10_to_base(uint64_t number, uint64_t base);
 
 /**
  * @brief Convert a number with a specific base to a number base 10.
  *
  * @param number
  * @param base
+ * @return uint64_t
  * @since v1.0.0
  */
-int convert_number_from_base_to_base_10(string_t number, unsigned int base);
+uint64_t convert_number_from_base_to_base_10(string_t number, uint64_t base);
 
 /**
  * @brief Convert a number with a specific base to a number of specific base.
@@ -74,8 +82,9 @@ int convert_number_from_base_to_base_10(string_t number, unsigned int base);
  * @param number
  * @param base_from
  * @param base_target
+ * @return string_t
  * @since v1.0.0
  */
-string_t convert_number_from_base_to_another(string_t number, int base_from, int base_target);
+string_t convert_number_from_base_to_another(string_t number, uint64_t base_from, uint64_t base_target);
 
 #endif

lib/date.c

@@ -0,0 +1,339 @@
+#include "date.h"
+
+struct date *date_copy(struct date *date_to_copy) {
+  struct date *date = malloc(sizeof(struct date));
+  if (date == NULL) {
+    perror("Error (date_copy)");
+    exit(EXIT_FAILURE);
+  }
+  date->year = date_to_copy->year;
+  date->month = date_to_copy->month;
+  date->day = date_to_copy->day;
+  date->hours = date_to_copy->hours;
+  date->minutes = date_to_copy->minutes;
+  date->seconds = date_to_copy->seconds;
+  date->milliseconds = date_to_copy->milliseconds;
+  date->timezone_utc_offset = date_to_copy->timezone_utc_offset;
+  return date;
+}
+
+bool date_get_is_valid_year(uint16_t year) {
+  return year <= 9999;
+}
+
+bool date_get_is_valid_month(uint8_t month) {
+  return month >= 1 && month <= 12;
+}
+
+bool date_get_is_valid_day(uint8_t day) {
+  return day >= 1 && day <= 31;
+}
+
+bool date_get_is_valid_hours(uint8_t hours) {
+  return hours <= 23;
+}
+
+bool date_get_is_valid_minutes(uint8_t minutes) {
+  return minutes <= 59;
+}
+
+bool date_get_is_valid_seconds(uint8_t seconds) {
+  return seconds <= 59;
+}
+
+bool date_get_is_valid_milliseconds(uint16_t milliseconds) {
+  return milliseconds <= 999;
+}
+
+bool date_get_is_valid_timezone_utc_offset(int8_t timezone_utc_offset) {
+  return timezone_utc_offset >= -12 && timezone_utc_offset <= 14;
+}
+
+bool date_get_is_valid(struct date *date) {
+  size_t date_days_of_month = date_get_days_of_month(date->month, date->year);
+  return (date_get_is_valid_month(date->month) &&
+          date_get_is_valid_day(date->day) &&
+          date->day <= date_days_of_month &&
+          date_get_is_valid_hours(date->hours) &&
+          date_get_is_valid_minutes(date->minutes) &&
+          date_get_is_valid_seconds(date->seconds) &&
+          date_get_is_valid_milliseconds(date->milliseconds) &&
+          date_get_is_valid_timezone_utc_offset(date->timezone_utc_offset));
+}
+
+string_t date_to_iso_string(struct date *date_original) {
+  struct date *date = date_copy(date_original);
+  date_to_utc(date);
+
+  size_t iso_string_length = 24;
+  string_t result = malloc(sizeof(char) * (iso_string_length + 1));
+
+  string_t year_string = string_zero_pad(date->year, 4);
+  string_t month_string = string_zero_pad(date->month, 2);
+  string_t day_string = string_zero_pad(date->day, 2);
+  string_t hours_string = string_zero_pad(date->hours, 2);
+  string_t minutes_string = string_zero_pad(date->minutes, 2);
+  string_t seconds_string = string_zero_pad(date->seconds, 2);
+  string_t milliseconds_string = string_zero_pad(date->milliseconds, 3);
+  sprintf(result, "%s-%s-%sT%s:%s:%s.%sZ", year_string, month_string, day_string, hours_string, minutes_string, seconds_string, milliseconds_string);
+  free(year_string);
+  free(month_string);
+  free(day_string);
+  free(hours_string);
+  free(minutes_string);
+  free(seconds_string);
+  free(milliseconds_string);
+
+  free(date);
+  return result;
+}
+
+string_t date_to_iso_string_without_time(struct date *date) {
+  size_t iso_string_length = 10;
+  string_t result = malloc(sizeof(char) * (iso_string_length + 1));
+  if (result == NULL) {
+    perror("Error (date_to_iso_string_without_time)");
+    exit(EXIT_FAILURE);
+  }
+
+  string_t year_string = string_zero_pad(date->year, 4);
+  string_t month_string = string_zero_pad(date->month, 2);
+  string_t day_string = string_zero_pad(date->day, 2);
+  sprintf(result, "%s-%s-%s", year_string, month_string, day_string);
+  free(year_string);
+  free(month_string);
+  free(day_string);
+
+  return result;
+}
+
+struct date *date_from_iso_string(string_t iso_string) {
+  struct date *date = malloc(sizeof(struct date));
+  if (date == NULL) {
+    perror("Error (date_from_iso_string)");
+    exit(EXIT_FAILURE);
+  }
+
+  string_t year_string = string_substring(iso_string, 0, 3);
+  date->year = (uint16_t)convert_string_to_number(year_string);
+  free(year_string);
+
+  string_t month_string = string_substring(iso_string, 5, 6);
+  date->month = (uint8_t)convert_string_to_number(month_string);
+  free(month_string);
+
+  string_t day_string = string_substring(iso_string, 8, 9);
+  date->day = (uint8_t)convert_string_to_number(day_string);
+  free(day_string);
+
+  string_t hours_string = string_substring(iso_string, 11, 12);
+  date->hours = (uint8_t)convert_string_to_number(hours_string);
+  free(hours_string);
+
+  string_t minutes_string = string_substring(iso_string, 14, 15);
+  date->minutes = (uint8_t)convert_string_to_number(minutes_string);
+  free(minutes_string);
+
+  string_t seconds_string = string_substring(iso_string, 17, 18);
+  date->seconds = (uint8_t)convert_string_to_number(seconds_string);
+  free(seconds_string);
+
+  string_t milliseconds_string = string_substring(iso_string, 20, 22);
+  date->milliseconds = (uint16_t)convert_string_to_number(milliseconds_string);
+  free(milliseconds_string);
+
+  date->timezone_utc_offset = 0;
+
+  return date;
+}
+
+uint8_t date_get_days_of_month(uint8_t month, uint16_t year) {
+  switch (month) {
+    case 1:
+      return 31;
+    case 2:
+      return date_get_is_leap_year(year) ? 29 : 28;
+    case 3:
+      return 31;
+    case 4:
+      return 30;
+    case 5:
+      return 31;
+    case 6:
+      return 30;
+    case 7:
+      return 31;
+    case 8:
+      return 31;
+    case 9:
+      return 30;
+    case 10:
+      return 31;
+    case 11:
+      return 30;
+    case 12:
+      return 31;
+    default:
+      return 0;
+  }
+}
+
+bool date_get_is_leap_year(uint16_t year) {
+  return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
+}
+
+uint64_t date_convert_milliseconds_to_seconds(uint16_t milliseconds) {
+  return milliseconds / MILLISECONDS_PER_SECOND;
+}
+
+uint64_t date_convert_seconds_to_milliseconds(uint64_t seconds) {
+  return seconds * MILLISECONDS_PER_SECOND;
+}
+
+uint64_t date_convert_days_to_seconds(uint64_t days) {
+  return days * SECONDS_PER_DAY;
+}
+
+uint64_t date_convert_hms_to_seconds(uint8_t hours, uint8_t minutes, uint8_t seconds) {
+  return (hours * SECONDS_PER_HOUR) + (minutes * SECONDS_PER_MINUTE) + seconds;
+}
+
+uint64_t date_to_total_seconds(struct date *date) {
+  uint64_t total_seconds = 0;
+
+  for (uint16_t year = 0; year < date->year; year++) {
+    total_seconds += 365 * SECONDS_PER_DAY;
+    if (date_get_is_leap_year(year)) {
+      total_seconds += SECONDS_PER_DAY;
+    }
+  }
+
+  for (uint8_t month = 1; month < date->month; month++) {
+    total_seconds += date_convert_days_to_seconds(date_get_days_of_month(month, date->year));
+  }
+
+  total_seconds += date_convert_days_to_seconds(date->day - 1);
+  total_seconds += date_convert_hms_to_seconds(date->hours, date->minutes, date->seconds);
+
+  return total_seconds;
+}
+
+uint64_t date_duration_seconds_between_2_dates(struct date *date1, struct date *date2) {
+  struct date *utc_date1 = date_copy(date1);
+  struct date *utc_date2 = date_copy(date2);
+  date_to_utc(utc_date1);
+  date_to_utc(utc_date2);
+
+  uint64_t total_seconds_date1 = date_to_total_seconds(utc_date1);
+  uint64_t total_seconds_date2 = date_to_total_seconds(utc_date2);
+
+  free(utc_date1);
+  free(utc_date2);
+
+  return total_seconds_date1 > total_seconds_date2 ? total_seconds_date1 - total_seconds_date2 : total_seconds_date2 - total_seconds_date1;
+}
+
+void date_add_hours(struct date *date, int64_t hours) {
+  if (hours == 0) {
+    return;
+  }
+  int64_t total_hours = date->hours + hours;
+  int64_t additional_days = total_hours / 24;
+  int64_t new_hours = total_hours % 24;
+
+  if (new_hours < 0) {
+    new_hours += 24;
+    additional_days -= 1;
+  }
+
+  date->hours = (uint8_t)new_hours;
+
+  if (additional_days != 0) {
+    date->day += additional_days;
+
+    while (date->day > date_get_days_of_month(date->month, date->year)) {
+      date->day -= date_get_days_of_month(date->month, date->year);
+      date->month++;
+
+      if (date->month > 12) {
+        date->month = 1;
+        date->year++;
+      }
+    }
+
+    while (date->day < 1) {
+      date->month--;
+      if (date->month < 1) {
+        date->month = 12;
+        date->year--;
+      }
+
+      date->day += date_get_days_of_month(date->month, date->year);
+    }
+  }
+}
+
+void date_add_days(struct date *date, int64_t days) {
+  date_add_hours(date, days * 24);
+}
+
+void date_to_utc(struct date *date) {
+  if (date->timezone_utc_offset == 0) {
+    return;
+  }
+  int8_t timezone_utc_offset = date->timezone_utc_offset;
+  date->timezone_utc_offset = 0;
+  date_add_hours(date, mathematics_opposite(timezone_utc_offset));
+}
+
+struct date *date_get_now_utc() {
+  struct date *date = malloc(sizeof(struct date));
+  if (date == NULL) {
+    perror("Error (date_get_now_utc)");
+    exit(EXIT_FAILURE);
+  }
+
+  time_t current_time = time(NULL);
+  struct tm *current_time_tm = gmtime(&current_time);
+
+  date->year = (uint16_t)(current_time_tm->tm_year + 1900);
+  date->month = (uint8_t)(current_time_tm->tm_mon + 1);
+  date->day = (uint8_t)current_time_tm->tm_mday;
+  date->hours = (uint8_t)current_time_tm->tm_hour;
+  date->minutes = (uint8_t)current_time_tm->tm_min;
+  date->seconds = (uint8_t)current_time_tm->tm_sec;
+  date->milliseconds = 0;
+  date->timezone_utc_offset = 0;
+
+  return date;
+}
+
+struct date *date_get_now_local() {
+  struct date *date = malloc(sizeof(struct date));
+  if (date == NULL) {
+    perror("Error (date_get_now_local)");
+    exit(EXIT_FAILURE);
+  }
+
+  time_t current_time = time(NULL);
+  struct tm *current_time_tm = localtime(&current_time);
+
+  date->year = (uint16_t)(current_time_tm->tm_year + 1900);
+  date->month = (uint8_t)(current_time_tm->tm_mon + 1);
+  date->day = (uint8_t)current_time_tm->tm_mday;
+  date->hours = (uint8_t)current_time_tm->tm_hour;
+  date->minutes = (uint8_t)current_time_tm->tm_min;
+  date->seconds = (uint8_t)current_time_tm->tm_sec;
+  date->milliseconds = 0;
+  date->timezone_utc_offset = 0;
+
+  return date;
+}
+
+uint16_t date_get_age(struct date *birth_date, struct date *current_date) {
+  uint16_t age = current_date->year - birth_date->year;
+  if (current_date->month < birth_date->month || (current_date->month == birth_date->month && current_date->day < birth_date->day)) {
+    age--;
+  }
+  return age;
+}

lib/date.h

@@ -0,0 +1,350 @@
+#ifndef __LIBCPROJECT_DATE__
+#define __LIBCPROJECT_DATE__
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "convert.h"
+#include "mathematics.h"
+#include "string.h"
+#include "types.h"
+
+#define SECONDS_PER_MINUTE 60
+#define SECONDS_PER_HOUR (60 * SECONDS_PER_MINUTE)
+#define SECONDS_PER_DAY (24 * SECONDS_PER_HOUR)
+#define MILLISECONDS_PER_SECOND 1000
+
+/**
+ * @brief Date object representing a single moment in time.
+ * @since v4.3.0
+ */
+struct date {
+  /**
+   * Year.
+   * Between [0, 9999] (inclusive).
+   * As per ISO 8601, a four-digit year [YYYY] and represents years from 0000 to 9999, year 0000 being equal to 1 BC and all others AD.
+   */
+  uint16_t year;
+
+  /**
+   * Month.
+   * Between [1, 12] (inclusive).
+   */
+  uint8_t month;
+
+  /**
+   * Day.
+   * Between [1, 31] (inclusive).
+   */
+  uint8_t day;
+
+  /**
+   * Hours.
+   * Between [0, 23] (inclusive).
+   */
+  uint8_t hours;
+
+  /**
+   * Minutes.
+   * Between [0, 59] (inclusive).
+   */
+  uint8_t minutes;
+
+  /**
+   * Seconds.
+   * Between [0, 59] (inclusive).
+   */
+  uint8_t seconds;
+
+  /**
+   * Milliseconds.
+   * Between [0, 999] (inclusive).
+   */
+  uint16_t milliseconds;
+
+  /**
+   * Timezone UTC offset.
+   * Between [-12, 14]
+   */
+  int8_t timezone_utc_offset;
+};
+
+/**
+ * @brief Return the copy of a date.
+ *
+ * @param date
+ * @return struct date*
+ * @since v4.3.0
+ */
+struct date *date_copy(struct date *date_to_copy);
+
+/**
+ * @brief Check if a year is valid, between [0, 9999] (inclusive).
+ *
+ * @param year
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_year(uint16_t year);
+
+/**
+ * @brief Check if a month is valid, between [1, 12] (inclusive).
+ *
+ * @param month
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_month(uint8_t month);
+
+/**
+ * @brief Check if a day is valid, between [1, 31] (inclusive).
+ *
+ * @param day
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_day(uint8_t day);
+
+/**
+ * @brief Check if hours are valid, between [0, 23] (inclusive).
+ *
+ * @param hours
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_hours(uint8_t hours);
+
+/**
+ * @brief Check if minutes are valid, between [0, 59] (inclusive).
+ *
+ * @param minutes
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_minutes(uint8_t minutes);
+
+/**
+ * @brief Check if seconds are valid, between [0, 59] (inclusive).
+ *
+ * @param seconds
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_seconds(uint8_t seconds);
+
+/**
+ * @brief Check if milliseconds are valid, between [0, 999] (inclusive).
+ *
+ * @param milliseconds
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_milliseconds(uint16_t milliseconds);
+
+/**
+ * @brief Check if the timezone UTC offset is valid, between [-12, 14] (inclusive).
+ *
+ * @param timezone_utc_offset
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid_timezone_utc_offset(int8_t timezone_utc_offset);
+
+/**
+ * @brief Check if the date is valid (all fields are possible).
+ *
+ * @param date
+ * @return bool
+ * @since v4.3.0
+ */
+bool date_get_is_valid(struct date *date);
+
+/**
+ * @brief String representing the date in the date time string format, a simplified format based on ISO 8601, which is always 24 characters long (`YYYY-MM-DDTHH:mm:ss.sssZ`). The timezone is always UTC, as denoted by the suffix `Z`.
+ *
+ * @param date
+ * @return string_t
+ *
+ * @code
+ * date_to_iso_string() // "2024-09-11T09:39:18.203Z"
+ * @endcode
+ *
+ * @since v4.3.0
+ */
+string_t date_to_iso_string(struct date *date);
+
+/**
+ * @brief String representing the date in the ISO 8601 format, without time information (`YYYY-MM-DD`).
+ *
+ * @param date
+ * @return string_t
+ *
+ * @code
+ * date_to_iso_string_without_time() // "2024-09-11"
+ * @endcode
+ *
+ * @since v4.3.0
+ */
+string_t date_to_iso_string_without_time(struct date *date);
+
+/**
+ * @brief Create a date from an ISO 8601 string, with the format `YYYY-MM-DDTHH:mm:ss.sssZ`.
+ *
+ * The timezone is always UTC, as denoted by the suffix `Z`.
+ *
+ * @param iso_string
+ * @return struct date*
+ * @since v4.3.0
+ */
+struct date *date_from_iso_string(string_t iso_string);
+
+/**
+ * @brief Get number of days in one month [1, 12].
+ *
+ * @param month
+ * @return uint8_t
+ * @since v4.3.0
+ */
+uint8_t date_get_days_of_month(uint8_t month, uint16_t year);
+
+/**
+ * @brief Determine if a year is a leap year.
+ *
+ * @param year
+ * @return bool
+ *
+ * @code
+ * date_is_leap_year(2020) // true
+ *
+ * date_is_leap_year(2021) // false
+ *
+ * date_is_leap_year(2022) // false
+ *
+ * date_is_leap_year(2023) // false
+ *
+ * date_is_leap_year(2024) // true
+ * @endcode
+ *
+ * @since v4.3.0
+ */
+bool date_get_is_leap_year(uint16_t year);
+
+/**
+ * @brief Convert milliseconds to seconds.
+ *
+ * @param milliseconds
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_milliseconds_to_seconds(uint16_t milliseconds);
+
+/**
+ * @brief Convert seconds to milliseconds.
+ *
+ * @param seconds
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_seconds_to_milliseconds(uint64_t seconds);
+
+/**
+ * @brief Convert days to seconds.
+ *
+ * @param days
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_days_to_seconds(uint64_t days);
+
+/**
+ * @brief Convert hours, minutes, and seconds to seconds.
+ *
+ * @param hours
+ * @param minutes
+ * @param seconds
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_convert_hms_to_seconds(uint8_t hours, uint8_t minutes, uint8_t seconds);
+
+/**
+ * @brief Convert a date to total seconds.
+ *
+ * @param date
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_to_total_seconds(struct date *date);
+
+/**
+ * @brief Calculate the duration in seconds between 2 dates.
+ *
+ * @param date1
+ * @param date2
+ * @return uint64_t
+ * @since v4.3.0
+ */
+uint64_t date_duration_seconds_between_2_dates(struct date *date1, struct date *date2);
+
+/**
+ * @brief Add hours to the date, managing the day, month, year changes if necessary.
+ *
+ * NOTE: Mutates the date.
+ *
+ * @param date
+ * @param hours
+ * @since v4.3.0
+ */
+void date_add_hours(struct date *date, int64_t hours);
+
+/**
+ * @brief Adds days to the date, managing month and year changes as needed.
+ *
+ * NOTE: Mutates the date.
+ *
+ * @param date The date to which days are being added.
+ * @param days The number of days to add.
+ * @since v4.3.0
+ */
+void date_add_days(struct date *date, int64_t days);
+
+/**
+ * @brief Transform the date with a Timezone UTC Offset to UTC (timezone_utc_offset = 0).
+ *
+ * NOTE: Mutates the date.
+ *
+ * @param date
+ * @since v4.3.0
+ */
+void date_to_utc(struct date *date);
+
+/**
+ * @brief Get the current date in UTC.
+ *
+ * @return struct date*
+ * @since v5.1.0
+ */
+struct date *date_get_now_utc();
+
+/**
+ * @brief Get the current date in local time.
+ *
+ * @return struct date*
+ * @since v5.1.0
+ */
+struct date *date_get_now_local();
+
+/**
+ * @brief Calculates the age of a person based on their birth date.
+ *
+ * @param birth_date
+ * @return uint16_t
+ * @since v5.1.0
+ */
+uint16_t date_get_age(struct date *birth_date, struct date *current_date);
+
+#endif

lib/filesystem.c

@@ -1,6 +1,6 @@
 #include "filesystem.h"
 
-int filesystem_read(string_t path, byte_t **file_content, off_t *file_size) {
+int filesystem_read(string_t path, byte_t **file_content, size_t *file_size) {
   int file_descriptor = open(path, O_RDONLY);
   if (file_descriptor == -1) {
     return -1;
@@ -15,7 +15,7 @@ int filesystem_read(string_t path, byte_t **file_content, off_t *file_size) {
   return 0;
 }
 
-int filesystem_write(string_t path, byte_t *file_content, off_t file_size) {
+int filesystem_write(string_t path, byte_t *file_content, size_t file_size) {
   int file_descriptor = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
   if (file_descriptor == -1) {
     return -1;

lib/filesystem.h

@@ -18,12 +18,13 @@
  *
  * @param path
  * @param file_content
- * @param file_size
+ * @param file_size The size of the file that was read (mutated by the function).
  * @retval -1 if the file does not exist or if there is an error.
  * @retval 0 for success.
+ * @return int
  * @since v1.0.0
  */
-int filesystem_read(string_t path, byte_t **file_content, off_t *file_size);
+int filesystem_read(string_t path, byte_t **file_content, size_t *file_size);
 
 /**
  * @brief Write the content to a file.
@@ -33,16 +34,16 @@ int filesystem_read(string_t path, byte_t **file_content, off_t *file_size);
  * @param file_size
  * @retval -1 if there is an error.
  * @retval 0 for success.
+ * @return int
  * @since v1.0.0
  */
-int filesystem_write(string_t path, byte_t *file_content, off_t file_size);
+int filesystem_write(string_t path, byte_t *file_content, size_t file_size);
 
 /**
  * @brief Check if a path exists.
  *
  * @param path
- * @retval true if the path exists.
+ * @return bool
- * @retval false if the path does not exist.
  * @since v3.1.0
  */
 bool filesystem_exists(string_t path);
@@ -54,6 +55,7 @@ bool filesystem_exists(string_t path);
  * @return int
  * @retval -1 if there is an error.
  * @retval 0 for success.
+ * @return int
  * @since v3.1.0
  */
 int filesystem_remove(string_t path);
@@ -64,6 +66,7 @@ int filesystem_remove(string_t path);
  * @param path
  * @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types
  * @see https://www.iana.org/assignments/media-types/media-types.xhtml
+ * @return string_t
  * @since v1.0.0
  */
 string_t filesystem_get_mimetype(string_t path);

lib/hash_map.c

@@ -40,7 +40,7 @@ uint64_t hash(string_t key, size_t capacity) {
     memcpy(&m, message + offset, sizeof(uint64_t));
     v3 ^= m;
 
-    for (int i = 0; i < 2; i++) {
+    for (uint8_t i = 0; i < 2; i++) {
       v0 = sip_round(v0, v1, v2, v3);
       v1 = ROTATE_LEFT(v1, 13);
       v2 = ROTATE_LEFT(v2, 16);
@@ -49,7 +49,7 @@ uint64_t hash(string_t key, size_t capacity) {
     }
 
     v2 ^= 0xff;
-    for (int i = 0; i < 4; i++) {
+    for (uint8_t i = 0; i < 4; i++) {
       v0 = sip_round(v0, v1, v2, v3);
       v1 = ROTATE_LEFT(v1, 13);
       v2 = ROTATE_LEFT(v2, 16);
@@ -90,7 +90,7 @@ uint64_t hash(string_t key, size_t capacity) {
 
   v3 ^= m;
 
-  for (int i = 0; i < 2; i++) {
+  for (uint8_t i = 0; i < 2; i++) {
     v0 = sip_round(v0, v1, v2, v3);
     v1 = ROTATE_LEFT(v1, 13);
     v2 = ROTATE_LEFT(v2, 16);
@@ -100,7 +100,7 @@ uint64_t hash(string_t key, size_t capacity) {
   v0 ^= m;
   v2 ^= 0xff;
 
-  for (int i = 0; i < 4; i++) {
+  for (uint8_t i = 0; i < 4; i++) {
     v0 = sip_round(v0, v1, v2, v3);
     v1 = ROTATE_LEFT(v1, 13);
     v2 = ROTATE_LEFT(v2, 16);

lib/hash_map.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_HASH_MAP__
 #define __LIBCPROJECT_HASH_MAP__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -34,22 +35,27 @@ struct hash_map_item {
 
 /**
  * @brief Hash function (using SipHash 1-3 algorithm).
- * @param key
- * @param capacity
  * @see https://en.wikipedia.org/wiki/SipHash
  * @see https://github.com/veorq/SipHash
+ *
+ * @param key
+ * @param capacity
+ * @return uint64_t
  * @since v2.0.0
  */
 uint64_t hash(string_t key, size_t capacity);
 
 /**
  * @brief Hash map initialization.
+ *
+ * @return struct hash_map*
  * @since v2.0.0
  */
 struct hash_map *hash_map_initialization();
 
 /**
  * @brief Add an item to the hash map.
+ *
  * @param hash_map
  * @param key
  * @param data
@@ -69,14 +75,17 @@ void hash_map_remove(struct hash_map *hash_map, string_t key);
  * @brief Get an item from the hash map.
  * @param hash_map
  * @param key
+ * @return void*
  * @since v2.0.0
  */
 void *hash_map_get(struct hash_map *hash_map, string_t key);
 
 /**
  * @brief Check if the hash map contains a key.
+ *
  * @param hash_map
  * @param key
+ * @return bool
  * @since v2.0.0
  */
 bool hash_map_contains_key(struct hash_map *hash_map, string_t key);
@@ -85,12 +94,15 @@ bool hash_map_contains_key(struct hash_map *hash_map, string_t key);
  * @brief Get the hash map keys.
  *
  * @param hash_map
+ * @return string_t*
  * @since v2.0.0
  */
 string_t *hash_map_get_keys(struct hash_map *hash_map);
 
 /**
  * @brief Frees the hash map.
+ *
+ * @param hash_map
  * @since v3.0.0
  */
 void hash_map_free(struct hash_map *hash_map);

lib/linked_list.c

@@ -1,8 +1,9 @@
 #include "linked_list.h"
 
 struct linked_list *linked_list_initialization() {
-  struct linked_list *list = malloc(sizeof(*list));
+  struct linked_list *list = malloc(sizeof(struct linked_list));
   if (list == NULL) {
+    perror("Error (linked_list_initialization)");
     exit(EXIT_FAILURE);
   }
   list->head = NULL;
@@ -11,8 +12,14 @@ struct linked_list *linked_list_initialization() {
 }
 
 struct linked_list_node *linked_list_add_in_head(struct linked_list *list, void *new_data) {
-  struct linked_list_node *node_new = malloc(sizeof(*node_new));
+  if (list == NULL) {
-  if (list == NULL || node_new == NULL) {
+    errno = EINVAL;
+    perror("Error (linked_list_add_in_head)");
+    exit(EXIT_FAILURE);
+  }
+  struct linked_list_node *node_new = malloc(sizeof(struct linked_list_node));
+  if (node_new == NULL) {
+    perror("Error (linked_list_add_in_head)");
     exit(EXIT_FAILURE);
   }
   node_new->data = new_data;
@@ -24,6 +31,8 @@ struct linked_list_node *linked_list_add_in_head(struct linked_list *list, void
 
 void linked_list_delete_in_head(struct linked_list *list) {
   if (list == NULL) {
+    errno = EINVAL;
+    perror("Error (linked_list_delete_in_head)");
     exit(EXIT_FAILURE);
   }
   if (list->head != NULL) {
@@ -35,11 +44,17 @@ void linked_list_delete_in_head(struct linked_list *list) {
 }
 
 struct linked_list_node *linked_list_add_after_last(struct linked_list *list, void *new_data) {
+  if (list == NULL) {
+    errno = EINVAL;
+    perror("Error (linked_list_add_after_last)");
+    exit(EXIT_FAILURE);
+  }
   if (list->head == NULL) {
     return linked_list_add_in_head(list, new_data);
   }
-  struct linked_list_node *node_new = malloc(sizeof(*node_new));
+  struct linked_list_node *node_new = malloc(sizeof(struct linked_list_node));
-  if (list == NULL || node_new == NULL) {
+  if (node_new == NULL) {
+    perror("Error (linked_list_add_after_last)");
     exit(EXIT_FAILURE);
   }
   node_new->data = new_data;

lib/linked_list.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_LINKED_LIST__
 #define __LIBCPROJECT_LINKED_LIST__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
@@ -13,7 +14,6 @@
  */
 struct linked_list {
   struct linked_list_node *head;
-
   size_t length;
 };
 
@@ -28,42 +28,61 @@ struct linked_list_node {
 
 /**
  * @brief Linked list initialization.
+ *
+ * @return struct linked_list*
  * @since v1.0.0
  */
 struct linked_list *linked_list_initialization();
 
 /**
  * @brief Add a new node in the head of the linked list.
+ *
+ * @param list
+ * @param new_value
+ * @return struct linked_list_node*
  * @since v1.0.0
  */
 struct linked_list_node *linked_list_add_in_head(struct linked_list *list, void *new_value);
 
 /**
  * @brief Delete node in the head of the linked list.
+ *
+ * @param list
  * @since v1.0.0
  */
 void linked_list_delete_in_head(struct linked_list *list);
 
 /**
  * @brief Add a new node in the tail of the linked list.
+ *
+ * @param list
+ * @param new_data
+ * @return struct linked_list_node*
  * @since v1.0.0
  */
 struct linked_list_node *linked_list_add_after_last(struct linked_list *list, void *new_data);
 
 /**
  * @brief Reverse the linked list by creating a new one.
+ *
+ * @param list
+ * @return struct linked_list*
  * @since v1.0.0
  */
 struct linked_list *linked_list_reverse(struct linked_list *list);
 
 /**
  * @brief Reverse the linked list by mutating it.
+ *
+ * @param list
  * @since v1.0.0
  */
 void linked_list_reverse_mutate(struct linked_list *list);
 
 /**
  * @brief Frees the linked list.
+ *
+ * @param list
  * @since v3.0.0
  */
 void linked_list_free(struct linked_list *list);

lib/mathematics.c

@@ -1,23 +1,23 @@
 #include "mathematics.h"
 
-bool mathematics_equals(const float number1, const float number2) {
+bool mathematics_equals(const float64_t number1, const float64_t number2) {
-  return (number1 - number2) < MATHEMATICS_FLOAT_PRECISION;
+  return (number1 - number2) < MATHEMATICS_DOUBLE_PRECISION;
 }
 
-unsigned long long mathematics_absolute_value(const long long number) {
+uint64_t mathematics_absolute_value(const int64_t number) {
   if (number >= 0) {
     return number;
   }
   return -number;
 }
 
-unsigned long long mathematics_pow(unsigned long long base, unsigned long long exponent) {
+uint64_t mathematics_pow(uint64_t base, uint64_t exponent) {
   return exponent == 0 ? 1 : base * mathematics_pow(base, exponent - 1);
 }
 
-float mathematics_root(float number, unsigned int nth_root) {
+float64_t mathematics_root(float64_t number, uint64_t nth_root) {
-  float result = number;
+  float64_t result = number;
-  float previous_result = 0;
+  float64_t previous_result = 0;
   while (!mathematics_equals(result, previous_result)) {
     result = (((nth_root - 1) * previous_result) + (number / mathematics_pow(result, nth_root - 1))) / nth_root;
     previous_result = result;
@@ -25,10 +25,46 @@ float mathematics_root(float number, unsigned int nth_root) {
   return result;
 }
 
-float mathematics_square_root(float number) {
+float64_t mathematics_square_root(float64_t number) {
   return mathematics_root(number, 2);
 }
 
-unsigned long long mathematics_factorial(unsigned long long number) {
+uint64_t mathematics_factorial(uint64_t number) {
   return number == 0 ? 1 : number * mathematics_factorial(number - 1);
 }
+
+int64_t mathematics_opposite(int64_t number) {
+  return number * -1;
+}
+
+int64_t mathematics_max(int64_t number1, int64_t number2) {
+  return number1 > number2 ? number1 : number2;
+}
+
+int64_t mathematics_max_values(int64_t *values, size_t values_length) {
+  int64_t max = 0;
+  if (values_length <= 0) {
+    return max;
+  }
+  max = values[0];
+  for (size_t index = 1; index < values_length; index++) {
+    max = mathematics_max(max, values[index]);
+  }
+  return max;
+}
+
+int64_t mathematics_min(int64_t number1, int64_t number2) {
+  return number1 > number2 ? number2 : number1;
+}
+
+int64_t mathematics_min_values(int64_t *values, size_t values_length) {
+  int64_t min = 0;
+  if (values_length <= 0) {
+    return min;
+  }
+  min = values[0];
+  for (size_t index = 1; index < values_length; index++) {
+    min = mathematics_min(min, values[index]);
+  }
+  return min;
+}

lib/mathematics.h

@@ -1,9 +1,11 @@
 #ifndef __LIBCPROJECT_MATHEMATICS__
 #define __LIBCPROJECT_MATHEMATICS__
 
-#define MATHEMATICS_FLOAT_PRECISION 0.00000001
+#define MATHEMATICS_DOUBLE_PRECISION 0.0000000001
 
+#include <errno.h>
 #include <stdbool.h>
+#include <stdlib.h>
 
 #include "types.h"
 
@@ -12,50 +14,111 @@
  *
  * @param number1
  * @param number2
+ * @return bool
  * @since v1.0.0
  */
-bool mathematics_equals(const float number1, const float number2);
+bool mathematics_equals(const float64_t number1, const float64_t number2);
 
 /**
  * @brief Get the absolute value of a number.
  *
  * @param number
+ * @return uint64_t
  * @since v1.0.0
  */
-unsigned long long mathematics_absolute_value(const long long number);
+uint64_t mathematics_absolute_value(const int64_t number);
 
 /**
  * @brief Calculates the power of a number.
  *
  * @param base
  * @param exponent
+ * @return uint64_t
  * @since v1.0.0
  */
-unsigned long long mathematics_pow(unsigned long long base, unsigned long long exponent);
+uint64_t mathematics_pow(uint64_t base, uint64_t exponent);
 
 /**
- * @brief Calculates the nth root of a number using Heron's method.
+ * @brief Calculates the nth root of a number.
  *
  * @param number
  * @param nth_root
+ * @return float64_t
  * @since v1.0.0
  */
-float mathematics_root(float number, unsigned int nth_root);
+float64_t mathematics_root(float64_t number, uint64_t nth_root);
 
 /**
  * @brief Calculates the square root of a number using Heron's method.
  *
  * @param number
+ * @return float64_t
  * @since v1.0.0
  */
-float mathematics_square_root(float number);
+float64_t mathematics_square_root(float64_t number);
 
 /**
  * @brief Calculates the factorial of a number.
  *
  * @param number
+ * @return uint64_t
  * @since v1.0.0
  */
-unsigned long long mathematics_factorial(unsigned long long number);
+uint64_t mathematics_factorial(uint64_t number);
+
+/**
+ * @brief Calulcates the opposite number (additive inverse).
+ *
+ * @param number
+ * @return int64_t
+ *
+ * @code
+ * mathematics_opposite(7) // -7
+ *
+ * mathematics_opposite(-7) // 7
+ * @endcode
+ * @since v4.3.0
+ */
+int64_t mathematics_opposite(int64_t number);
+
+/**
+ * @brief Returns the largest number between 2 numbers.
+ *
+ * @param number1
+ * @param number2
+ * @return int64_t
+ * @since v4.3.0
+ */
+int64_t mathematics_max(int64_t number1, int64_t number2);
+
+/**
+ * @brief Returns the largest number between multiple numbers. If the array is empty, returns 0.
+ *
+ * @param values
+ * @param values_length
+ * @return int64_t
+ * @since v4.3.0
+ */
+int64_t mathematics_max_values(int64_t *values, size_t values_length);
+
+/**
+ * @brief Returns the smallest number between 2 numbers.
+ *
+ * @param number1
+ * @param number2
+ * @return int64_t
+ * @since v4.3.0
+ */
+int64_t mathematics_min(int64_t number1, int64_t number2);
+
+/**
+ * @brief Returns the smallest number between multiple numbers. If the array is empty, returns 0.
+ *
+ * @param values
+ * @param values_length
+ * @return int64_t
+ * @since v4.3.0
+ */
+int64_t mathematics_min_values(int64_t *values, size_t values_length);
 
 #endif

lib/queue.c

@@ -1,8 +1,9 @@
 #include "queue.h"
 
 struct queue *queue_initialization() {
-  struct queue *queue = malloc(sizeof(*queue));
+  struct queue *queue = malloc(sizeof(struct queue));
   if (queue == NULL) {
+    perror("Error (queue_initialization)");
     exit(EXIT_FAILURE);
   }
   queue->first = NULL;
@@ -11,8 +12,14 @@ struct queue *queue_initialization() {
 }
 
 void queue_push(struct queue *queue, void *data) {
-  struct queue_node *node_new = malloc(sizeof(*node_new));
+  if (queue == NULL) {
-  if (queue == NULL || node_new == NULL) {
+    errno = EINVAL;
+    perror("Error (queue_push)");
+    exit(EXIT_FAILURE);
+  }
+  struct queue_node *node_new = malloc(sizeof(struct queue_node));
+  if (node_new == NULL) {
+    perror("Error (queue_push)");
     exit(EXIT_FAILURE);
   }
   node_new->data = data;
@@ -31,6 +38,8 @@ void queue_push(struct queue *queue, void *data) {
 
 void *queue_pop(struct queue *queue) {
   if (queue == NULL) {
+    errno = EINVAL;
+    perror("Error (queue_pop)");
     exit(EXIT_FAILURE);
   }
   struct queue_node *node = queue->first;
@@ -46,6 +55,8 @@ void *queue_pop(struct queue *queue) {
 
 void queue_free(struct queue *queue) {
   if (queue == NULL) {
+    errno = EINVAL;
+    perror("Error (queue_free)");
     exit(EXIT_FAILURE);
   }
   struct queue_node *node = queue->first;

lib/queue.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_QUEUE__
 #define __LIBCPROJECT_QUEUE__
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -26,24 +27,34 @@ struct queue_node {
 
 /**
  * @brief Queue initialization.
+ *
+ * @return struct queue*
  * @since v1.0.0
  */
 struct queue *queue_initialization();
 
 /**
  * @brief Push data to queue.
+ *
+ * @param queue
+ * @param data
  * @since v1.0.0
  */
 void queue_push(struct queue *queue, void *data);
 
 /**
  * @brief Pop data from queue.
+ *
+ * @param queue
+ * @return void*
  * @since v1.0.0
  */
 void *queue_pop(struct queue *queue);
 
 /**
  * @brief Frees the queue.
+ *
+ * @param queue
  * @since v3.0.0
  */
 void queue_free(struct queue *queue);

lib/stack.c

@@ -1,8 +1,9 @@
 #include "stack.h"
 
 struct stack *stack_initialization() {
-  struct stack *stack = malloc(sizeof(*stack));
+  struct stack *stack = malloc(sizeof(struct stack));
   if (stack == NULL) {
+    perror("Error (stack_initialization)");
     exit(EXIT_FAILURE);
   }
   stack->first = NULL;
@@ -11,8 +12,14 @@ struct stack *stack_initialization() {
 }
 
 void stack_push(struct stack *stack, void *data) {
-  struct stack_node *node_new = malloc(sizeof(*node_new));
+  if (stack == NULL) {
-  if (stack == NULL || data == NULL) {
+    errno = EINVAL;
+    perror("Error (stack_push)");
+    exit(EXIT_FAILURE);
+  }
+  struct stack_node *node_new = malloc(sizeof(struct stack_node));
+  if (data == NULL) {
+    perror("Error (stack_push)");
     exit(EXIT_FAILURE);
   }
   node_new->data = data;
@@ -23,6 +30,8 @@ void stack_push(struct stack *stack, void *data) {
 
 void *stack_pop(struct stack *stack) {
   if (stack == NULL) {
+    errno = EINVAL;
+    perror("Error (stack_pop)");
     exit(EXIT_FAILURE);
   }
   struct stack_node *node = stack->first;
@@ -38,6 +47,8 @@ void *stack_pop(struct stack *stack) {
 
 void stack_free(struct stack *stack) {
   if (stack == NULL) {
+    errno = EINVAL;
+    perror("Error (stack_free)");
     exit(EXIT_FAILURE);
   }
   struct stack_node *node = stack->first;

lib/stack.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_STACK__
 #define __LIBCPROJECT_STACK__
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -26,24 +27,34 @@ struct stack_node {
 
 /**
  * @brief Stack initialization.
+ *
+ * @return struct stack*
  * @since v1.0.0
  */
 struct stack *stack_initialization();
 
 /**
  * @brief Push data to stack.
+ *
+ * @param stack
+ * @param data
  * @since v1.0.0
  */
 void stack_push(struct stack *stack, void *data);
 
 /**
  * @brief Pop data from stack.
+ *
+ * @param stack
+ * @return void*
  * @since v1.0.0
  */
 void *stack_pop(struct stack *stack);
 
 /**
  * @brief Frees the stack.
+ *
+ * @param stack
  * @since v3.0.0
  */
 void stack_free(struct stack *stack);

lib/string.c

@@ -1,135 +1,110 @@
 #include "string.h"
 
-size_t string_get_length(const string_t string_value) {
+size_t string_get_length(const string_t string) {
   size_t length = 0;
-  while (string_value[length] != '\0') {
+  while (string[length] != '\0') {
     length++;
   }
   return length;
 }
 
-string_t string_to_uppercase(string_t string_value) {
+void string_to_uppercase(string_t string) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  string_t result = malloc(sizeof(char) * (string_length + 1));
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
   for (size_t index = 0; index < string_length; index++) {
-    result[index] = character_to_upper(string_value[index]);
+    string[index] = character_to_upper(string[index]);
   }
-  result[string_length] = '\0';
+  string[string_length] = '\0';
-  return result;
 }
 
-string_t string_to_lowercase(string_t string_value) {
+void string_to_lowercase(string_t string) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  string_t result = malloc(sizeof(char) * (string_length + 1));
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
   for (size_t index = 0; index < string_length; index++) {
-    result[index] = character_to_lower(string_value[index]);
+    string[index] = character_to_lower(string[index]);
   }
-  result[string_length] = '\0';
+  string[string_length] = '\0';
-  return result;
 }
 
-string_t string_replace(string_t string_value, char search, char replace) {
+void string_replace(string_t string, char search, char replace) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  string_t result = malloc(sizeof(char) * (string_length + 1));
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
   for (size_t index = 0; index < string_length; index++) {
-    bool is_search_value = search == string_value[index];
+    bool is_search_value = search == string[index];
     if (is_search_value) {
-      result[index] = replace;
+      string[index] = replace;
     } else {
-      result[index] = string_value[index];
+      string[index] = string[index];
     }
   }
-  result[string_length] = '\0';
+  string[string_length] = '\0';
-  return result;
 }
 
-string_t string_trim_start(string_t string_value, char character) {
+void string_remove_character(string_t string, char search) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  string_t result = malloc(sizeof(char) * (string_length + 1));
+  for (size_t index = 0; index < string_length; index++) {
-  if (result == NULL) {
+    if (string[index] == search) {
-    exit(EXIT_FAILURE);
+      for (size_t index_string = index; index_string < string_length; index_string++) {
+        string[index_string] = string[index_string + 1];
+      }
+      string_length--;
+      index--;
+    }
   }
+  string[string_length] = '\0';
+}
+
+void string_trim_start(string_t string, char character) {
+  size_t string_length = string_get_length(string);
   size_t index_space = 0;
-  while (string_value[index_space] == character) {
+  while (string[index_space] == character) {
     index_space++;
   }
-  for (size_t index = index_space; index < string_length; index++) {
+  for (size_t index = 0; index < string_length - index_space; index++) {
-    result[index - index_space] = string_value[index];
+    string[index] = string[index + index_space];
   }
-  result[string_length - index_space] = '\0';
+  string[string_length - index_space] = '\0';
-  return result;
 }
 
-string_t string_trim_end(string_t string_value, char character) {
+void string_trim_end(string_t string, char character) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  string_t result = malloc(sizeof(char) * (string_length + 1));
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
   size_t index_space = string_length - 1;
-  while (string_value[index_space] == character) {
+  while (string[index_space] == character) {
     index_space--;
   }
-  for (size_t index = 0; index < index_space + 1; index++) {
+  string[index_space + 1] = '\0';
-    result[index] = string_value[index];
-  }
-  result[index_space + 1] = '\0';
-  return result;
 }
 
-string_t string_trim(string_t string_value, char character) {
+void string_trim(string_t string, char character) {
-  string_t result_start = string_trim_start(string_value, character);
+  string_trim_start(string, character);
-  string_t result = string_trim_end(result_start, character);
+  string_trim_end(string, character);
-  free(result_start);
-  return result;
 }
 
-string_t string_copy(const string_t source) {
+string_t string_copy(const string_t string) {
-  size_t source_length = string_get_length(source);
+  size_t source_length = string_get_length(string);
   string_t copy = malloc(sizeof(char) * (source_length + 1));
   if (copy == NULL) {
+    perror("Error (string_copy)");
     exit(EXIT_FAILURE);
   }
   size_t index;
   for (index = 0; index < source_length; index++) {
-    copy[index] = source[index];
+    copy[index] = string[index];
   }
   copy[index] = '\0';
   return copy;
 }
 
-string_t string_capitalize(string_t string_value) {
+void string_capitalize(string_t string) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  string_t result = malloc(sizeof(char) * (string_length + 1));
+  if (string_length == 0) {
-  if (result == NULL) {
+    return;
-    exit(EXIT_FAILURE);
   }
-  for (size_t index = 0; index < string_length; index++) {
+  string[0] = character_to_upper(string[0]);
-    bool is_first_character = index == 0;
-    if (is_first_character) {
-      result[index] = character_to_upper(string_value[index]);
-    } else {
-      result[index] = string_value[index];
-    }
-  }
-  result[string_length] = '\0';
-  return result;
 }
 
-size_t string_total_occurrences_of_character(string_t string_value, char character) {
+size_t string_total_occurrences_of_character(string_t string, char character) {
   size_t result = 0;
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   for (size_t index = 0; index < string_length; index++) {
-    char current_character = string_value[index];
+    char current_character = string[index];
     if (current_character == character) {
       result += 1;
     }
@@ -137,21 +112,17 @@ size_t string_total_occurrences_of_character(string_t string_value, char charact
   return result;
 }
 
-string_t string_reverse(const string_t string_value) {
+void string_reverse(const string_t string) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
-  size_t index = 0;
+  size_t index_start = 0;
-  string_t result = malloc(sizeof(char) * (string_length + 1));
+  size_t index_end = string_length - 1;
-  if (result == NULL) {
+  while (index_start < index_end) {
-    exit(EXIT_FAILURE);
+    char temporary = string[index_start];
+    string[index_start] = string[index_end];
+    string[index_end] = temporary;
+    index_start++;
+    index_end--;
   }
-  size_t result_index = 0;
-  for (index = string_length - 1; index > 0; index--) {
-    result[result_index] = string_value[index];
-    result_index++;
-  }
-  result[result_index] = string_value[index];
-  result[string_length] = '\0';
-  return result;
 }
 
 bool string_equals(const string_t string1, const string_t string2) {
@@ -166,11 +137,11 @@ bool string_equals(const string_t string1, const string_t string2) {
   return is_equal;
 }
 
-bool string_get_is_integer(const string_t string_value) {
+bool string_get_is_integer(const string_t string) {
   size_t index = 0;
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   bool is_integer = string_length >= 1;
-  if (is_integer && string_value[0] == '-') {
+  if (is_integer && string[0] == '-') {
     if (string_length == 1) {
       is_integer = false;
     } else {
@@ -178,7 +149,7 @@ bool string_get_is_integer(const string_t string_value) {
     }
   }
   while (index < string_length && is_integer) {
-    if (!character_get_is_digit(string_value[index])) {
+    if (!character_get_is_digit(string[index])) {
       is_integer = false;
     }
     index++;
@@ -186,36 +157,38 @@ bool string_get_is_integer(const string_t string_value) {
   return is_integer;
 }
 
-string_t* string_split(const string_t string_value, char separator, size_t* result_size) {
+string_t* string_split(const string_t string, char separator, size_t* result_size) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   size_t index_string = 0;
   size_t index_current = 0;
   size_t index_result = 0;
   string_t current = malloc(sizeof(char) * (string_length + 1));
   string_t* result = NULL;
   if (current == NULL) {
+    perror("Error (string_split)");
     exit(EXIT_FAILURE);
   }
   while (index_string < string_length) {
-    if (string_value[index_string] == separator) {
+    if (string[index_string] == separator) {
       current[index_current] = '\0';
       result = realloc(result, sizeof(string_t) * (index_result + 1));
       if (result == NULL) {
+        perror("Error (string_split)");
         exit(EXIT_FAILURE);
       }
       result[index_result] = string_copy(current);
       index_result++;
       index_current = 0;
     } else {
-      current[index_current] = string_value[index_string];
+      current[index_current] = string[index_string];
       index_current++;
     }
     index_string++;
   }
-
   current[index_current] = '\0';
   result = realloc(result, sizeof(string_t) * (index_result + 1));
   if (result == NULL) {
+    perror("Error (string_split)");
     exit(EXIT_FAILURE);
   }
   result[index_result] = string_copy(current);
@@ -230,8 +203,9 @@ string_t string_join(string_t* array, const char separator, size_t array_length)
     total_length += string_get_length(array[index_array]);
   }
   size_t string_length = total_length + (array_length - 1);
-  string_t string_value = malloc(sizeof(char) * (string_length + 1));
+  string_t string = malloc(sizeof(char) * (string_length + 1));
-  if (string_value == NULL) {
+  if (string == NULL) {
+    perror("Error (string_join)");
     exit(EXIT_FAILURE);
   }
   size_t current_index = 0;
@@ -239,48 +213,45 @@ string_t string_join(string_t* array, const char separator, size_t array_length)
     string_t substring = array[index_array];
     size_t substring_length = string_get_length(substring);
     for (size_t index_substring = 0; index_substring < substring_length; index_substring++) {
-      string_value[current_index] = substring[index_substring];
+      string[current_index] = substring[index_substring];
       current_index++;
     }
     bool is_last_character = index_array == (array_length - 1);
     if (!is_last_character) {
-      string_value[current_index] = separator;
+      string[current_index] = separator;
       current_index++;
     }
   }
-  string_value[string_length] = '\0';
+  string[string_length] = '\0';
-  return string_value;
+  return string;
 }
 
-string_t string_concatenate(string_t string1, string_t string2) {
+void string_concatenate(string_t* destination, string_t source) {
-  size_t string1_length = string_get_length(string1);
+  size_t destination_length = string_get_length(*destination);
-  size_t string2_length = string_get_length(string2);
+  size_t source_length = string_get_length(source);
-  size_t result_length = string1_length + string2_length;
+  size_t new_length = destination_length + source_length;
-  string_t result = malloc(sizeof(char) * (result_length + 1));
+  *destination = realloc(*destination, sizeof(char) * (new_length + 1));
-  if (result == NULL) {
+  if (*destination == NULL) {
+    perror("Error (string_concatenate)");
     exit(EXIT_FAILURE);
   }
-  size_t index_string1 = 0;
+  size_t index_destination = destination_length;
-  for (; index_string1 < string1_length; index_string1++) {
+  for (size_t index_source = 0; index_source < source_length; index_source++) {
-    result[index_string1] = string1[index_string1];
+    (*destination)[index_destination++] = source[index_source];
   }
-  for (size_t index_string2 = 0; index_string2 < string2_length; index_string2++) {
+  (*destination)[index_destination] = '\0';
-    result[index_string1 + index_string2] = string2[index_string2];
-  }
-  result[result_length] = '\0';
-  return result;
 }
 
-bool string_get_has_unique_characters(const string_t string_value) {
+bool string_get_has_unique_characters(const string_t string) {
   bool has_unique = true;
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   struct hash_map* characters_already_seen = hash_map_initialization();
   string_t* keys = malloc(sizeof(string_t) * string_length);
   for (size_t index = 0; index < string_length; index++) {
     keys[index] = NULL;
   }
   for (size_t index = 0; index < string_length && has_unique; index++) {
-    char character = string_value[index];
+    char character = string[index];
     keys[index] = convert_character_to_string(character);
     string_t key = keys[index];
     if (hash_map_contains_key(characters_already_seen, key)) {
@@ -299,24 +270,24 @@ bool string_get_has_unique_characters(const string_t string_value) {
   return has_unique;
 }
 
-string_t string_substring(const string_t string_value, size_t index_start, size_t index_end) {
+string_t string_substring(const string_t string, size_t index_start, size_t index_end) {
   size_t substring_length = index_end - index_start + 1;
   string_t result = malloc(sizeof(char) * (substring_length + 1));
   for (size_t index = 0; index < substring_length; index++) {
-    result[index] = string_value[index_start + index];
+    result[index] = string[index_start + index];
   }
   result[substring_length] = '\0';
   return result;
 }
 
-bool string_get_is_substring(const string_t string_value, const string_t substring) {
+bool string_get_is_substring(const string_t string, const string_t substring) {
   bool is_substring = false;
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   size_t substring_length = string_get_length(substring);
   for (size_t index_string = 0; index_string < string_length && !is_substring; index_string++) {
     size_t index_substring = 0;
     size_t index_considered = index_string;
-    while (index_substring < substring_length && string_value[index_considered] == substring[index_substring]) {
+    while (index_substring < substring_length && string[index_considered] == substring[index_substring]) {
       index_substring++;
       index_considered++;
     }
@@ -325,7 +296,7 @@ bool string_get_is_substring(const string_t string_value, const string_t substri
   return is_substring;
 }
 
-string_t string_get_formatted_number(const long long number, string_t separator) {
+string_t string_get_formatted_number(const int64_t number, string_t separator) {
   string_t number_string_temp = convert_number_to_string(number);
   string_t number_string = number_string_temp;
   bool is_negative = number_string_temp[0] == '-';
@@ -337,6 +308,7 @@ string_t string_get_formatted_number(const long long number, string_t separator)
   size_t formatted_length = number_string_length + (number_string_length - 1) / 3;
   string_t result = malloc(sizeof(char) * (formatted_length + 1));
   if (result == NULL) {
+    perror("Error (string_get_formatted_number)");
     exit(EXIT_FAILURE);
   }
   size_t count = 0;
@@ -356,23 +328,21 @@ string_t string_get_formatted_number(const long long number, string_t separator)
   }
   free(number_string);
   result[formatted_length] = '\0';
-  string_t new_result = string_reverse(result);
+  string_reverse(result);
-  free(result);
   if (is_negative) {
-    string_t dash = convert_character_to_string('-');
+    string_t negative_result = convert_character_to_string('-');
-    string_t negative_result = string_concatenate(dash, new_result);
+    string_concatenate(&negative_result, result);
-    free(new_result);
+    free(result);
-    free(dash);
     return negative_result;
   }
-  return new_result;
+  return result;
 }
 
-string_t string_get_last_occurence_of_character(const string_t string_value, char character) {
+string_t string_get_last_occurence_of_character(const string_t string, char character) {
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   size_t index_last_occurrence = SIZE_MAX;
   for (size_t index = 0; index < string_length; index++) {
-    if (string_value[index] == character) {
+    if (string[index] == character) {
       index_last_occurrence = index;
     }
   }
@@ -381,35 +351,92 @@ string_t string_get_last_occurence_of_character(const string_t string_value, cha
   }
   string_t result = malloc(sizeof(char) * (string_length - index_last_occurrence + 1));
   if (result == NULL) {
+    perror("Error (string_get_last_occurence_of_character)");
     exit(EXIT_FAILURE);
   }
   size_t index_result = 0;
   for (size_t index = index_last_occurrence; index < string_length; index++) {
-    result[index_result++] = string_value[index];
+    result[index_result++] = string[index];
   }
   result[index_result] = '\0';
   return result;
 }
 
-bool string_starts_with(const string_t string_value, const string_t prefix) {
+bool string_starts_with(const string_t string, const string_t prefix) {
   bool starts_with = true;
   size_t prefix_length = string_get_length(prefix);
   for (size_t index = 0; index < prefix_length && starts_with; index++) {
-    starts_with = string_value[index] == prefix[index];
+    starts_with = string[index] == prefix[index];
   }
   return starts_with;
 }
 
-bool string_ends_with(const string_t string_value, const string_t prefix) {
+bool string_ends_with(const string_t string, const string_t prefix) {
   bool ends_with = true;
-  size_t string_length = string_get_length(string_value);
+  size_t string_length = string_get_length(string);
   size_t prefix_length = string_get_length(prefix);
   size_t index_string = string_length - 1;
   size_t index_prefix = prefix_length - 1;
   while (index_prefix > 0 && ends_with) {
-    ends_with = string_value[index_string] == prefix[index_prefix];
+    ends_with = string[index_string] == prefix[index_prefix];
     index_string--;
     index_prefix--;
   }
   return ends_with;
 }
+
+size_t string_position_of(const string_t string, const char character) {
+  size_t position_found = 0;
+  size_t string_length = string_get_length(string);
+  for (size_t index = 0; index < string_length && position_found == 0; index++) {
+    if (string[index] == character) {
+      position_found = index + 1;
+    }
+  }
+  return position_found;
+}
+
+size_t string_last_position_of(const string_t string, const char character) {
+  size_t position_found = 0;
+  size_t string_length = string_get_length(string);
+  while (string_length > 0 && position_found == 0) {
+    if (string[string_length - 1] == character) {
+      position_found = string_length;
+    }
+    string_length--;
+  }
+  return position_found;
+}
+
+string_t string_pad_start(const string_t string, const string_t pad_string, size_t target_length) {
+  string_t result = malloc(sizeof(char) * (target_length + 1));
+  size_t initial_length = string_get_length(string);
+  size_t left_length = target_length - initial_length;
+  if (target_length <= initial_length) {
+    left_length = 0;
+  }
+  size_t pad_length = string_get_length(pad_string);
+  size_t count_pad_string = 0;
+  size_t index_initial_string = 0;
+  for (size_t index = 0; index < target_length; index++) {
+    if (index < left_length) {
+      size_t index_pad_string = count_pad_string % pad_length;
+      result[index] = pad_string[index_pad_string];
+      count_pad_string += 1;
+    } else {
+      result[index] = string[index_initial_string];
+      index_initial_string += 1;
+    }
+  }
+  result[target_length] = '\0';
+  return result;
+}
+
+string_t string_zero_pad(uint64_t number, size_t places) {
+  string_t number_string = convert_number_to_string((int64_t)number);
+  string_t pad_string = string_copy("0");
+  string_t result = string_pad_start(number_string, pad_string, places);
+  free(pad_string);
+  free(number_string);
+  return result;
+}

lib/string.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_STRING__
 #define __LIBCPROJECT_STRING__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -13,122 +14,155 @@
 /**
  * @brief Return the length of a string (excluding '\0').
  *
- * @param string_value
+ * @param string
+ * @return size_t
  * @since v1.0.0
  */
-size_t string_get_length(const string_t string_value);
+size_t string_get_length(const string_t string);
 
 /**
  * @brief Converts all the alphabetic characters in a string to uppercase.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_to_uppercase(string_t string_value);
+void string_to_uppercase(string_t string);
 
 /**
  * @brief Converts all the alphabetic characters in a string to lowercase.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_to_lowercase(string_t string_value);
+void string_to_lowercase(string_t string);
 
 /**
  * @brief Replace all the occurrences of search value into replace value in the string.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @param search A character search value.
  * @param replace A character containing the text to replace for match.
  * @since v1.0.0
  */
-string_t string_replace(string_t string_value, char search, char replace);
+void string_replace(string_t string, char search, char replace);
+
+/**
+ * @brief Removes all the occurrences of a character in a string.
+ *
+ * NOTE: Mutates the string.
+ *
+ * @param string
+ * @param search A character search value.
+ * @since v4.1.0
+ */
+void string_remove_character(string_t string, char search);
 
 /**
  * @brief Removes all `character` from the start of a string.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_trim_start(string_t string_value, char character);
+void string_trim_start(string_t string, char character);
 
 /**
  * @brief Removes all `character` from the end of a string.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_trim_end(string_t string_value, char character);
+void string_trim_end(string_t string, char character);
 
 /**
  * @brief Removes all `character` from the start and end of a string.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_trim(string_t string_value, char character);
+void string_trim(string_t string, char character);
 
 /**
  * @brief Return the copy of a string.
  *
- * @param string_value
+ * @param string
+ * @return string_t
  * @since v1.0.0
  */
-string_t string_copy(const string_t string_value);
+string_t string_copy(const string_t string);
 
 /**
  * @brief Capitalizes the string.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_capitalize(string_t string_value);
+void string_capitalize(string_t string);
 
 /**
  * @brief Returns the total number of occurrences of the given character in the string.
  *
- * @param string_value
+ * @param string
  * @param character
+ * @return size_t
  * @since v1.0.0
  */
-size_t string_total_occurrences_of_character(string_t string_value, char character);
+size_t string_total_occurrences_of_character(string_t string, char character);
 
 /**
- * @brief Reverse the characters in an array.
+ * @brief Reverse the characters in a string.
  *
- * @param string_value
+ * NOTE: Mutates the string.
+ *
+ * @param string
  * @since v1.0.0
  */
-string_t string_reverse(const string_t string_value);
+void string_reverse(const string_t string);
 
 /**
  * @brief Check if two strings are equals.
  *
  * @param string1
  * @param string2
- * @return true if the strings are equals, false otherwise.
+ * @return true if the strings are equals.
+ * @return false if the strings are not equals.
  * @since v1.0.0
  */
 bool string_equals(const string_t string1, const string_t string2);
 
 /**
- * @brief Check if the string is a integer.
+ * @brief Check if the string is an integer.
  *
- * @param string_value
+ * @param string
- * @return true if the string is a integer, false otherwise.
+ * @return true if the string is an integer.
+ * @return false if the string is not an integer.
  * @since v1.0.0
  */
-bool string_get_is_integer(const string_t string_value);
+bool string_get_is_integer(const string_t string);
 
 /**
  * @brief Split a string into substrings using the specified separator and return them as an array and update the pointer `result_size` to the resulting size of the created array.
  *
- * @param string_value
+ * @param string
  * @param separator
  * @param result_size
+ * @return string_t*
  * @since v1.0.0
  */
-string_t* string_split(const string_t string_value, char separator, size_t* result_size);
+string_t* string_split(const string_t string, char separator, size_t* result_size);
 
 /**
  * @brief Adds all the elements of an array into a string, separated by the specified separator string.
@@ -136,6 +170,7 @@ string_t* string_split(const string_t string_value, char separator, size_t* resu
  * @param array
  * @param separator
  * @param array_length
+ * @return string_t
  * @since v1.0.0
  */
 string_t string_join(string_t* array, const char separator, size_t array_length);
@@ -143,17 +178,20 @@ string_t string_join(string_t* array, const char separator, size_t array_length)
 /**
  * @brief Concatenate two strings.
  *
- * @param string1
+ * NOTE: Mutates the string `destination`.
- * @param string2
+ *
+ * @param destination
+ * @param source
  * @since v1.0.0
  */
-string_t string_concatenate(string_t string1, string_t string2);
+void string_concatenate(string_t* destination, string_t source);
 
 /**
  * @brief Check if a string contains only unique characters.
  *
  * @param string
- * @return true if string contains only unique characters, false otherwise.
+ * @return true if string contains only unique characters.
+ * @return false if string contains duplicate characters.
  * @since v1.0.0
  */
 bool string_get_has_unique_characters(const string_t string);
@@ -161,63 +199,130 @@ bool string_get_has_unique_characters(const string_t string);
 /**
  * @brief Returns the part of the string between the start and end indexes (both included).
  *
- * @param string_value
+ * @param string
  * @param index_start
  * @param index_end
+ * @return string_t
  * @since v1.0.0
  */
-string_t string_substring(const string_t string_value, size_t index_start, size_t index_end);
+string_t string_substring(const string_t string, size_t index_start, size_t index_end);
 
 /**
  * @brief Check if a string contains a substring.
  *
- * @param string_value
+ * @param string
  * @param substring
- * @return true if the string contains the substring, false otherwise.
+ * @return true if the string contains the substring.
+ * @return false if the string does not contain the substring.
  * @since v1.0.0
  */
-bool string_get_is_substring(const string_t string_value, const string_t substring);
+bool string_get_is_substring(const string_t string, const string_t substring);
 
 /**
  * @brief Format a number to a string with specified separator.
  *
  * @param number
  * @param separator
- * @since v1.0.0
+ * @return string_t
+ *
  * @code
  * string_get_formatted_number(1000, " ") // "1 000"
+ *
  * string_get_formatted_number(1000, ",") // "1,000"
  * @endcode
+ * @since v1.0.0
  */
-string_t string_get_formatted_number(const long long number, string_t separator);
+string_t string_get_formatted_number(const int64_t number, string_t separator);
 
 /**
  * @brief Returns a pointer to the last occurrence of character in the string.
  *
- * @param string_value
+ * @param string
  * @param character
+ * @return string_t
  * @since v1.0.0
  */
-string_t string_get_last_occurence_of_character(const string_t string_value, char character);
+string_t string_get_last_occurence_of_character(const string_t string, char character);
 
 /**
  * @brief Check if a string starts with a substring.
  *
- * @param string_value
+ * @param string
  * @param prefix
- * @return true if the string starts with the substring, false otherwise.
+ * @return true if the string starts with the substring.
+ * @return false if the string does not start with the substring.
  * @since v1.0.0
  */
-bool string_starts_with(const string_t string_value, const string_t prefix);
+bool string_starts_with(const string_t string, const string_t prefix);
 
 /**
  * @brief Check if a string ends with a substring.
  *
- * @param string_value
+ * @param string
  * @param prefix
- * @return true if the string ends with the substring, false otherwise.
+ * @return true if the string ends with the substring.
+ * @return false if the string does not end with the substring.
  * @since v1.0.0
  */
-bool string_ends_with(const string_t string_value, const string_t prefix);
+bool string_ends_with(const string_t string, const string_t prefix);
+
+/**
+ * @brief Returns the position (index + 1) within the string of the first occurrence of the specified substring (0 if not found).
+ *
+ * @param string
+ * @param substring
+ * @return size_t
+ *
+ * @code
+ * string_position_of("hello world", 'e') // 2
+ * @endcode
+ * @since v4.2.0
+ */
+size_t string_position_of(const string_t string, const char character);
+
+/**
+ * @brief Returns the position (index + 1) within the string of the last occurrence of the specified substring (0 if not found).
+ *
+ * @param string
+ * @param character
+ * @return size_t
+ *
+ * @code
+ * string_last_position_of("hello world", 'o') // 8
+ * @endcode
+ * @since v4.2.0
+ */
+size_t string_last_position_of(const string_t string, const char character);
+
+/**
+ * @brief Pads a `string` with another `pad_string` (multiple times, if needed) until the resulting string reaches the `target_length`. The padding is applied from the start (left) of the string.
+ *
+ * @param string The string to pad.
+ * @param pad_string The string to pad the current string with, to the left.
+ * @param target_length
+ * @return string_t
+ *
+ * @code
+ * string_pad_start("hello", " ", 10) // "     hello"
+ * @endcode
+ * @since v4.3.0
+ */
+string_t string_pad_start(const string_t string, const string_t pad_string, size_t target_length);
+
+/**
+ * @brief Pad a number with zeros.
+ *
+ * @param number
+ * @param places
+ * @return string_t
+ *
+ * @code
+ * string_zero_pad(1, 2) // "01"
+ *
+ * string_zero_pad(10, 2) // "10"
+ * @endcode
+ * @since v4.3.0
+ */
+string_t string_zero_pad(uint64_t number, size_t places);
 
 #endif

lib/terminal.c

@@ -3,39 +3,32 @@
 string_t terminal_input() {
   char character;
   size_t length = 1;
-  string_t string_value = malloc(length * sizeof(char));
+  string_t string = malloc(length * sizeof(char));
-  if (string_value == NULL) {
+  if (string == NULL) {
+    perror("Error (terminal_input)");
     exit(EXIT_FAILURE);
   }
-  *string_value = '\0';
+  *string = '\0';
   while ((character = getchar()) != '\n' && character != EOF) {
     length++;
-    string_value = realloc(string_value, length * sizeof(char));
+    string = realloc(string, length * sizeof(char));
-    if (string_value == NULL) {
+    if (string == NULL) {
+      perror("Error (terminal_input)");
       exit(EXIT_FAILURE);
     }
-    character_append(string_value, character);
+    character_append(string, character);
   }
-  return string_value;
+  return string;
-}
-
-void terminal_print_array(void* array, size_t array_size, size_t element_size, void (*print_element)(void*)) {
-  printf("[");
-  for (size_t index = 0; index < array_size; index++) {
-    void* element = (char*)array + index * element_size;
-    print_element(element);
-    bool is_last = index == array_size - 1;
-    if (!is_last) {
-      printf(", ");
-    }
-  }
-  printf("]\n");
 }
 
 void terminal_print_int(void* value) {
   printf("%d", *(int*)value);
 }
 
+void terminal_print_bool(void* value) {
+  printf("%s", *(bool*)value ? "true" : "false");
+}
+
 void terminal_print_long(void* value) {
   printf("%ld", *(long*)value);
 }
@@ -44,23 +37,78 @@ void terminal_print_unsigned_long(void* value) {
   printf("%lu", *(unsigned long*)value);
 }
 
+void terminal_print_float(void* value) {
+  printf("%f", *(float*)value);
+}
+
+void terminal_print_double(void* value) {
+  printf("%f", *(double*)value);
+}
+
+void terminal_print_int8_t(void* value) {
+  printf("%d", *(int8_t*)value);
+}
+
+void terminal_print_int16_t(void* value) {
+  printf("%d", *(int16_t*)value);
+}
+
+void terminal_print_int32_t(void* value) {
+  printf("%d", *(int32_t*)value);
+}
+
+void terminal_print_int64_t(void* value) {
+  printf("%ld", *(int64_t*)value);
+}
+
+void terminal_print_uint8_t(void* value) {
+  printf("%u", *(uint8_t*)value);
+}
+
+void terminal_print_uint16_t(void* value) {
+  printf("%u", *(uint16_t*)value);
+}
+
+void terminal_print_uint32_t(void* value) {
+  printf("%u", *(uint32_t*)value);
+}
+
+void terminal_print_uint64_t(void* value) {
+  printf("%lu", *(uint64_t*)value);
+}
+
 void terminal_print_char(void* value) {
-  printf("%c", *(char*)value);
+  printf("%c", *(string_t)value);
+}
+
+void terminal_print_array(void* array, size_t array_size, size_t element_size, void (*print_element)(void*)) {
+  printf("[");
+  for (size_t index = 0; index < array_size; index++) {
+    void* element = (string_t)array + index * element_size;
+    print_element(element);
+    bool is_last = index == array_size - 1;
+    if (!is_last) {
+      printf(", ");
+    }
+  }
+  printf("]\n");
 }
 
 void terminal_print_string(void* value) {
-  printf("%s", (char*)value);
+  printf("%s", (string_t)value);
 }
 
 void terminal_print_stack(struct stack* stack, void (*print_element)(void*)) {
   if (stack == NULL) {
+    errno = EINVAL;
+    perror("Error (terminal_print_stack)");
     exit(EXIT_FAILURE);
   }
   struct stack_node* node_current = stack->first;
   while (node_current != NULL) {
     printf("|\t");
-    void* element = (char*)node_current->data;
+    void* element = node_current->data;
-    print_element(&element);
+    print_element(element);
     node_current = node_current->next;
     printf("\t|\n");
   }
@@ -68,13 +116,15 @@ void terminal_print_stack(struct stack* stack, void (*print_element)(void*)) {
 
 void terminal_print_queue(struct queue* queue, void (*print_element)(void*)) {
   if (queue == NULL) {
+    errno = EINVAL;
+    perror("Error (terminal_print_queue)");
     exit(EXIT_FAILURE);
   }
   struct queue_node* node_current = queue->first;
   while (node_current != NULL) {
     printf("|\t");
-    void* element = (char*)node_current->data;
+    void* element = node_current->data;
-    print_element(&element);
+    print_element(element);
     node_current = node_current->next;
     printf("\t|\n");
   }
@@ -82,13 +132,15 @@ void terminal_print_queue(struct queue* queue, void (*print_element)(void*)) {
 
 void terminal_print_linked_list(struct linked_list* linked_list, void (*print_element)(void*)) {
   if (linked_list == NULL) {
+    errno = EINVAL;
+    perror("Error (terminal_print_linked_list)");
     exit(EXIT_FAILURE);
   }
   struct linked_list_node* node_current = linked_list->head;
   while (node_current != NULL) {
-    void* element = (char*)node_current->data;
+    void* element = (string_t)node_current->data;
     node_current = node_current->next;
-    print_element(&element);
+    print_element(element);
     printf(" -> ");
   }
   printf("NULL\n");
@@ -96,6 +148,8 @@ void terminal_print_linked_list(struct linked_list* linked_list, void (*print_el
 
 void terminal_print_hash_map(struct hash_map* hash_map, void (*print_element)(void*)) {
   if (hash_map == NULL) {
+    errno = EINVAL;
+    perror("Error (terminal_print_hash_map)");
     exit(EXIT_FAILURE);
   }
   printf("{\n");
@@ -106,12 +160,21 @@ void terminal_print_hash_map(struct hash_map* hash_map, void (*print_element)(vo
     printf("\t\"");
     terminal_print_string(key);
     printf("\" -> ");
-    print_element(&value);
+    print_element(value);
     printf("\n");
   }
   printf("}\n");
+  free(keys);
 }
 
 void terminal_print_array_list(struct array_list* list, void (*print_element)(void*)) {
-  terminal_print_array(list->data, list->size, sizeof(void*), print_element);
+  printf("[");
+  for (size_t index = 0; index < list->size; index++) {
+    void* element = list->data[index];
+    print_element(element);
+    if (index < list->size - 1) {
+      printf(", ");
+    }
+  }
+  printf("]\n");
 }

lib/terminal.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_TERMINAL__
 #define __LIBCPROJECT_TERMINAL__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -16,21 +17,12 @@
 
 /**
  * @brief Read a line from stdin.
+ *
+ * @return string_t
  * @since v1.0.0
  */
 string_t terminal_input();
 
-/**
- * @brief Print an array.
- *
- * @param array
- * @param array_size
- * @param element_size
- * @param print_element
- * @since v1.0.0
- */
-void terminal_print_array(void* array, size_t array_size, size_t element_size, void (*print_element)(void*));
-
 /**
  * @brief Print a int.
  *
@@ -39,6 +31,14 @@ void terminal_print_array(void* array, size_t array_size, size_t element_size, v
  */
 void terminal_print_int(void* value);
 
+/**
+ * @brief Print a boolean.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_bool(void* value);
+
 /**
  * @brief Print a long.
  *
@@ -55,6 +55,86 @@ void terminal_print_long(void* value);
  */
 void terminal_print_unsigned_long(void* value);
 
+/**
+ * @brief Print a float.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_float(void* value);
+
+/**
+ * @brief Print a double.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_double(void* value);
+
+/**
+ * @brief Print a int8_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_int8_t(void* value);
+
+/**
+ * @brief Print a int16_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_int16_t(void* value);
+
+/**
+ * @brief Print a int32_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_int32_t(void* value);
+
+/**
+ * @brief Print a int64_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_int64_t(void* value);
+
+/**
+ * @brief Print a uint8_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_uint8_t(void* value);
+
+/**
+ * @brief Print a uint16_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_uint16_t(void* value);
+
+/**
+ * @brief Print a uint32_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_uint32_t(void* value);
+
+/**
+ * @brief Print a uint64_t.
+ *
+ * @param value
+ * @since v5.0.0
+ */
+void terminal_print_uint64_t(void* value);
+
 /**
  * @brief Print a char.
  *
@@ -63,6 +143,17 @@ void terminal_print_unsigned_long(void* value);
  */
 void terminal_print_char(void* value);
 
+/**
+ * @brief Print an array.
+ *
+ * @param array
+ * @param array_size
+ * @param element_size
+ * @param print_element
+ * @since v1.0.0
+ */
+void terminal_print_array(void* array, size_t array_size, size_t element_size, void (*print_element)(void*));
+
 /**
  * @brief Print a string.
  *
@@ -110,7 +201,7 @@ void terminal_print_hash_map(struct hash_map* hash_map, void (*print_element)(vo
 /**
  * @brief Print an array list.
  *
- * @param array_list
+ * @param list
  * @param print_element
  * @since v3.0.0
  */

lib/types.h

@@ -7,4 +7,7 @@ typedef uint8_t byte_t;
 
 typedef char* string_t;
 
+typedef float float32_t;
+typedef double float64_t;
+
 #endif

libcproject.h

@@ -2,8 +2,10 @@
 #define __LIBCPROJECT__
 
 #include "lib/array_list.h"
+#include "lib/assert.h"
 #include "lib/character.h"
 #include "lib/convert.h"
+#include "lib/date.h"
 #include "lib/filesystem.h"
 #include "lib/hash_map.h"
 #include "lib/linked_list.h"

main.c

@@ -4,8 +4,135 @@
 #include "libcproject.h"
 
 int main() {
-  string_t string_value = "Hello, world!";
+  int integer = 5;
-  printf("%s\n", string_value);
+  terminal_print_int(&integer);
-  printf("string_length = %ld\n", string_get_length(string_value));
+  printf("\n");
+
+  bool boolean = true;
+  printf("terminal_print_bool: ");
+  terminal_print_bool(&boolean);
+  printf(", ");
+  boolean = false;
+  terminal_print_bool(&boolean);
+  printf("\n");
+
+  long integer_long = 5;
+  printf("terminal_print_long: ");
+  terminal_print_long(&integer_long);
+  printf("\n");
+
+  unsigned long integer_unsigned_long = 5;
+  printf("terminal_print_unsigned_long: ");
+  terminal_print_unsigned_long(&integer_unsigned_long);
+  printf("\n");
+
+  float floating_point = 5.5;
+  printf("terminal_print_float: ");
+  terminal_print_float(&floating_point);
+  printf("\n");
+
+  double floating_point_double = 5.5;
+  printf("terminal_print_double: ");
+  terminal_print_double(&floating_point_double);
+  printf("\n");
+
+  int8_t integer_8 = 5;
+  printf("terminal_print_int8_t: ");
+  terminal_print_int8_t(&integer_8);
+  printf("\n");
+
+  int16_t integer_16 = 5;
+  printf("terminal_print_int16_t: ");
+  terminal_print_int16_t(&integer_16);
+  printf("\n");
+
+  int32_t integer_32 = 5;
+  printf("terminal_print_int32_t: ");
+  terminal_print_int32_t(&integer_32);
+  printf("\n");
+
+  int64_t integer_64 = 5;
+  printf("terminal_print_int64_t: ");
+  terminal_print_int64_t(&integer_64);
+  printf("\n");
+
+  uint8_t integer_unsigned_8 = 5;
+  printf("terminal_print_uint8_t: ");
+  terminal_print_uint8_t(&integer_unsigned_8);
+  printf("\n");
+
+  uint16_t integer_unsigned_16 = 5;
+  printf("terminal_print_uint16_t: ");
+  terminal_print_uint16_t(&integer_unsigned_16);
+  printf("\n");
+
+  uint32_t integer_unsigned_32 = 5;
+  printf("terminal_print_uint32_t: ");
+  terminal_print_uint32_t(&integer_unsigned_32);
+  printf("\n");
+
+  uint64_t integer_unsigned_64 = 5;
+  printf("terminal_print_uint64_t: ");
+  terminal_print_uint64_t(&integer_unsigned_64);
+  printf("\n");
+
+  char character = 'c';
+  printf("terminal_print_char: ");
+  terminal_print_char(&character);
+  printf("\n");
+
+  int array[] = {1, 2, 3, 4, 5};
+  printf("terminal_print_array: ");
+  terminal_print_array(array, 5, sizeof(int), terminal_print_int);
+
+  string_t string = "Hello, world!";
+  printf("terminal_print_string: ");
+  terminal_print_string(string);
+  printf("\n");
+
+  struct stack* stack = stack_initialization();
+  stack_push(stack, &integer);
+  printf("terminal_print_stack: ");
+  terminal_print_stack(stack, terminal_print_int);
+  stack_free(stack);
+
+  struct queue* queue = queue_initialization();
+  queue_push(queue, &integer);
+  printf("terminal_print_queue: ");
+  terminal_print_queue(queue, terminal_print_int);
+  queue_free(queue);
+
+  struct linked_list* linked_list = linked_list_initialization();
+  linked_list_add_after_last(linked_list, string);
+  linked_list_add_after_last(linked_list, string);
+  printf("terminal_print_linked_list: ");
+  terminal_print_linked_list(linked_list, terminal_print_string);
+  linked_list_free(linked_list);
+
+  struct hash_map* hash_map = hash_map_initialization();
+  hash_map_add(hash_map, "key", &integer);
+  printf("terminal_print_hash_map: ");
+  terminal_print_hash_map(hash_map, terminal_print_int);
+  hash_map_free(hash_map);
+
+  struct array_list* array_list = array_list_initialization();
+  array_list_add(array_list, &integer);
+  array_list_add(array_list, &integer);
+  printf("terminal_print_array_list: ");
+  terminal_print_array_list(array_list, terminal_print_int);
+  array_list_free(array_list);
+
+  struct date* date = date_get_now_utc();
+  string_t iso_string = date_to_iso_string(date);
+  printf("date_get_now_utc = %s\n", iso_string);
+  free(iso_string);
+  free(date);
+
+  date = date_get_now_local();
+  iso_string = date_to_iso_string(date);
+  printf("date_get_now_local = %s\n", iso_string);
+  free(iso_string);
+  free(date);
+
   return EXIT_SUCCESS;
 }

set_version.c

@@ -8,14 +8,15 @@ int main(int argc, string_t* argv) {
     fprintf(stderr, "Usage: %s <version>\n", argv[0]);
     return EXIT_FAILURE;
   }
-  string_t content = "#ifndef __LIBCPROJECT_VERSION__\n";
+  string_t content = string_copy("#ifndef __LIBCPROJECT_VERSION__\n");
-  content = string_concatenate(content, "#define __LIBCPROJECT_VERSION__ \"");
+  string_concatenate(&content, "#define __LIBCPROJECT_VERSION__ \"");
-  content = string_concatenate(content, argv[1]);
+  string_concatenate(&content, argv[1]);
-  content = string_concatenate(content, "\"\n\n");
+  string_concatenate(&content, "\"\n\n");
-  content = string_concatenate(content, "#endif\n");
+  string_concatenate(&content, "#endif\n");
   int result = filesystem_write("./version.h", (byte_t*)content, string_get_length(content));
   if (result == -1) {
     fprintf(stderr, "Error: Could not write to file.\n");
+    perror("Error (set_version)");
     return EXIT_FAILURE;
   }
   printf("Success: Version set to %s.\n", argv[1]);

test/array_list_test.c

@@ -34,4 +34,15 @@ void array_list_test() {
   assert(array_list_get(list, 100) == (void *)95);
 
   array_list_free(list);
+
+  list = array_list_initialization();
+  array_list_add(list, (void *)'a');
+  array_list_add(list, (void *)'b');
+  array_list_add(list, (void *)'c');
+  array_list_remove(list, 1);
+  assert(array_list_get(list, 0) == (void *)'a');
+  assert(array_list_get(list, 1) == (void *)'c');
+  assert(list->size == 2);
+
+  array_list_free(list);
 }

test/character_test.h

@@ -6,7 +6,6 @@
 #include <stdlib.h>
 
 #include "libcproject.h"
-#include "test.h"
 
 void character_test();
 

test/convert_test.c

@@ -10,7 +10,7 @@ void convert_test() {
 }
 
 void convert_character_to_string_test() {
-  char* result = convert_character_to_string('a');
+  string_t result = convert_character_to_string('a');
   assert(assert_string_equal(result, "a"));
   free(result);
 
@@ -77,7 +77,7 @@ void convert_string_to_number_test() {
 }
 
 void convert_number_to_string_test() {
-  char* result = convert_number_to_string(0);
+  string_t result = convert_number_to_string(0);
   assert(assert_string_equal(result, "0"));
   free(result);
 
@@ -143,7 +143,7 @@ void convert_number_to_string_test() {
 }
 
 void convert_number_from_base_to_another_test() {
-  char* result = convert_number_from_base_to_another("15", 10, 16);
+  string_t result = convert_number_from_base_to_another("15", 10, 16);
   assert(assert_string_equal(result, "F"));
   free(result);
 

test/convert_test.h

@@ -6,7 +6,6 @@
 #include <stdlib.h>
 
 #include "libcproject.h"
-#include "test.h"
 
 void convert_test();
 

test/date_test.c

@@ -0,0 +1,191 @@
+#include "date_test.h"
+
+void date_test() {
+  date_copy_test();
+  date_to_iso_string_test();
+  date_to_iso_string_without_time_test();
+  date_from_iso_string_test();
+  date_get_is_leap_year_test();
+  date_duration_seconds_between_2_dates_test();
+  date_to_utc_test();
+  date_get_age_test();
+}
+
+void date_copy_test() {
+  struct date *date = malloc(sizeof(struct date));
+  date->year = 2024;
+  date->month = 9;
+  date->day = 10;
+  date->hours = 20;
+  date->minutes = 34;
+  date->seconds = 25;
+  date->milliseconds = 76;
+  date->timezone_utc_offset = 0;
+
+  struct date *date2 = date_copy(date);
+  assert(date != date2);
+  assert(date->year == date2->year);
+  assert(date->month == date2->month);
+  assert(date->day == date2->day);
+  assert(date->hours == date2->hours);
+  assert(date->minutes == date2->minutes);
+  assert(date->seconds == date2->seconds);
+  assert(date->milliseconds == date2->milliseconds);
+  assert(date->timezone_utc_offset == date2->timezone_utc_offset);
+
+  date->year = 2025;
+  assert(date->year == 2025);
+  assert(date2->year == 2024);
+
+  free(date);
+  free(date2);
+}
+
+void date_to_iso_string_test() {
+  struct date *date = malloc(sizeof(struct date));
+  date->year = 2024;
+  date->month = 9;
+  date->day = 10;
+  date->hours = 20;
+  date->minutes = 34;
+  date->seconds = 25;
+  date->milliseconds = 76;
+  date->timezone_utc_offset = 0;
+
+  string_t iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-09-10T20:34:25.076Z"));
+  free(iso_string);
+
+  free(date);
+}
+
+void date_to_iso_string_without_time_test() {
+  struct date *date = malloc(sizeof(struct date));
+  date->year = 2024;
+  date->month = 9;
+  date->day = 10;
+  date->hours = 20;
+  date->minutes = 34;
+  date->seconds = 25;
+  date->milliseconds = 76;
+  date->timezone_utc_offset = 0;
+
+  string_t iso_string = date_to_iso_string_without_time(date);
+  assert(assert_string_equal(iso_string, "2024-09-10"));
+  free(iso_string);
+
+  free(date);
+}
+
+void date_from_iso_string_test() {
+  string_t iso_string = "2024-09-10T20:34:25.076Z";
+  struct date *date = date_from_iso_string(iso_string);
+  assert(date->year == 2024);
+  assert(date->month == 9);
+  assert(date->day == 10);
+  assert(date->hours == 20);
+  assert(date->minutes == 34);
+  assert(date->seconds == 25);
+  assert(date->milliseconds == 76);
+  assert(date->timezone_utc_offset == 0);
+
+  free(date);
+}
+
+void date_get_is_leap_year_test() {
+  assert(date_get_is_leap_year(2020));
+  assert(!date_get_is_leap_year(2021));
+  assert(!date_get_is_leap_year(2022));
+  assert(!date_get_is_leap_year(2023));
+  assert(date_get_is_leap_year(2024));
+}
+
+void date_duration_seconds_between_2_dates_test() {
+  struct date *date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  struct date *date2 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 0);
+  free(date1);
+  free(date2);
+
+  date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date2 = date_from_iso_string("2024-09-10T23:34:26.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 10801);
+  free(date1);
+  free(date2);
+
+  date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date2 = date_from_iso_string("2024-09-10T20:48:25.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 840);
+  free(date1);
+  free(date2);
+
+  date1 = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date2 = date_from_iso_string("2024-09-10T20:34:38.076Z");
+  assert(date_duration_seconds_between_2_dates(date1, date2) == 13);
+  free(date1);
+  free(date2);
+}
+
+void date_to_utc_test() {
+  struct date *date = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date->timezone_utc_offset = 3;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  string_t iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-09-10T17:34:25.076Z"));
+  free(iso_string);
+  free(date);
+
+  date = date_from_iso_string("2024-09-10T20:34:25.076Z");
+  date->timezone_utc_offset = -3;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-09-10T23:34:25.076Z"));
+  free(iso_string);
+  free(date);
+
+  date = date_from_iso_string("2024-01-01T00:00:00.000Z");
+  date->timezone_utc_offset = 3;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2023-12-31T21:00:00.000Z"));
+  free(iso_string);
+  free(date);
+
+  date = date_from_iso_string("2023-12-31T21:00:00.000Z");
+  date->timezone_utc_offset = -4;
+  date_to_utc(date);
+  assert(date->timezone_utc_offset == 0);
+  iso_string = date_to_iso_string(date);
+  assert(assert_string_equal(iso_string, "2024-01-01T01:00:00.000Z"));
+  free(iso_string);
+  free(date);
+}
+
+void date_get_age_test() {
+  struct date *birth_date = date_from_iso_string("1980-02-20T00:00:00.000Z");
+  struct date *current_date = date_from_iso_string("2018-03-20T00:00:00.000Z");
+  assert(date_get_age(birth_date, current_date) == 38);
+  free(birth_date);
+  free(current_date);
+
+  birth_date = date_from_iso_string("1980-07-20T00:00:00.000Z");
+  current_date = date_from_iso_string("2018-03-20T00:00:00.000Z");
+  assert(date_get_age(birth_date, current_date) == 37);
+  free(birth_date);
+  free(current_date);
+
+  birth_date = date_from_iso_string("1980-03-20T00:00:00.000Z");
+  current_date = date_from_iso_string("2018-03-20T00:00:00.000Z");
+  assert(date_get_age(birth_date, current_date) == 38);
+  free(birth_date);
+  free(current_date);
+
+  birth_date = date_from_iso_string("1980-03-25T00:00:00.000Z");
+  current_date = date_from_iso_string("2018-03-20T00:00:00.000Z");
+  assert(date_get_age(birth_date, current_date) == 37);
+  free(birth_date);
+  free(current_date);
+}

test/date_test.h

@@ -0,0 +1,26 @@
+#ifndef __DATE_TEST__
+#define __DATE_TEST__
+
+#include <assert.h>
+
+#include "libcproject.h"
+
+void date_test();
+
+void date_copy_test();
+
+void date_to_iso_string_test();
+
+void date_to_iso_string_without_time_test();
+
+void date_from_iso_string_test();
+
+void date_get_is_leap_year_test();
+
+void date_duration_seconds_between_2_dates_test();
+
+void date_to_utc_test();
+
+void date_get_age_test();
+
+#endif

test/main.c

@@ -4,6 +4,7 @@
 #include "array_list_test.h"
 #include "character_test.h"
 #include "convert_test.h"
+#include "date_test.h"
 #include "hash_map_test.h"
 #include "linked_list_test.h"
 #include "mathematics_test.h"
@@ -15,6 +16,7 @@ int main() {
   array_list_test();
   character_test();
   convert_test();
+  date_test();
   hash_map_test();
   linked_list_test();
   mathematics_test();

test/mathematics_test.c

@@ -6,6 +6,11 @@ void mathematics_test() {
   mathematics_root_test();
   mathematics_square_root_test();
   mathematics_factorial_test();
+  mathematics_opposite_test();
+  mathematics_max_test();
+  mathematics_max_values_test();
+  mathematics_min_test();
+  mathematics_min_values_test();
 }
 
 void mathematics_absolute_value_test() {
@@ -56,3 +61,38 @@ void mathematics_factorial_test() {
   assert(mathematics_factorial(9) == 362880);
   assert(mathematics_factorial(10) == 3628800);
 }
+
+void mathematics_opposite_test() {
+  assert(mathematics_opposite(-7) == 7);
+  assert(mathematics_opposite(7) == -7);
+}
+
+void mathematics_max_test() {
+  assert(mathematics_max(0, 0) == 0);
+  assert(mathematics_max(0, 1) == 1);
+  assert(mathematics_max(2, 0) == 2);
+  assert(mathematics_max(54, 37) == 54);
+}
+
+void mathematics_max_values_test() {
+  int64_t values[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+  assert(mathematics_max_values(values, 10) == 9);
+
+  int64_t values2[] = {8, 6, 4, 7};
+  assert(mathematics_max_values(values2, 4) == 8);
+}
+
+void mathematics_min_test() {
+  assert(mathematics_min(0, 0) == 0);
+  assert(mathematics_min(3, 5) == 3);
+  assert(mathematics_min(2, 1) == 1);
+  assert(mathematics_min(54, 37) == 37);
+}
+
+void mathematics_min_values_test() {
+  int64_t values[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+  assert(mathematics_min_values(values, 10) == 0);
+
+  int64_t values2[] = {9, 6, 8, 7};
+  assert(mathematics_min_values(values2, 4) == 6);
+}

test/mathematics_test.h

@@ -17,4 +17,14 @@ void mathematics_square_root_test();
 
 void mathematics_factorial_test();
 
+void mathematics_opposite_test();
+
+void mathematics_max_test();
+
+void mathematics_max_values_test();
+
+void mathematics_min_test();
+
+void mathematics_min_values_test();
+
 #endif

test/string_test.c

@@ -5,6 +5,7 @@ void string_test() {
   string_to_uppercase_test();
   string_to_lowercase_test();
   string_replace_test();
+  string_remove_character_test();
   string_trim_start_test();
   string_trim_end_test();
   string_trim_test();
@@ -24,52 +25,64 @@ void string_test() {
   string_get_last_occurence_of_character_test();
   string_starts_with_test();
   string_ends_with_test();
+  string_position_of_test();
+  string_last_position_of_test();
+  string_pad_start_test();
+  string_zero_pad_test();
 }
 
 void string_get_length_test() {
   string_t string = "Hello World!";
   size_t string_length = string_get_length(string);
   assert(string_length == 12);
+  assert(strlen(string) == string_length);
 }
 
 void string_to_uppercase_test() {
-  string_t string = "heLlO world";
+  string_t string = string_copy("heLlO world");
-  string = string_to_uppercase(string);
+  string_to_uppercase(string);
   assert(assert_string_equal(string, "HELLO WORLD"));
   free(string);
 }
 
 void string_to_lowercase_test() {
-  string_t string = "HellO WoRLd";
+  string_t string = string_copy("HellO WoRLd");
-  string = string_to_lowercase(string);
+  string_to_lowercase(string);
   assert(assert_string_equal(string, "hello world"));
   free(string);
 }
 
 void string_replace_test() {
-  string_t string = "hello world";
+  string_t string = string_copy("hello world");
-  string = string_replace(string, 'l', 'z');
+  string_replace(string, 'l', 'z');
   assert(assert_string_equal(string, "hezzo worzd"));
   free(string);
 }
 
+void string_remove_character_test() {
+  string_t string = string_copy("hello world");
+  string_remove_character(string, 'l');
+  assert(assert_string_equal(string, "heo word"));
+  free(string);
+}
+
 void string_trim_start_test() {
-  string_t string = "      hello world      ";
+  string_t string = string_copy("      hello world      ");
-  string = string_trim_start(string, ' ');
+  string_trim_start(string, ' ');
   assert(assert_string_equal(string, "hello world      "));
   free(string);
 }
 
 void string_trim_end_test() {
-  string_t string = "      hello world      ";
+  string_t string = string_copy("      hello world      ");
-  string = string_trim_end(string, ' ');
+  string_trim_end(string, ' ');
   assert(assert_string_equal(string, "      hello world"));
   free(string);
 }
 
 void string_trim_test() {
-  string_t string = "      hello world      ";
+  string_t string = string_copy("      hello world      ");
-  string = string_trim(string, ' ');
+  string_trim(string, ' ');
   assert(assert_string_equal(string, "hello world"));
   free(string);
 }
@@ -86,8 +99,8 @@ void string_copy_test() {
 }
 
 void string_capitalize_test() {
-  string_t string = "hello world";
+  string_t string = string_copy("hello world");
-  string = string_capitalize(string);
+  string_capitalize(string);
   assert(assert_string_equal(string, "Hello world"));
   free(string);
 }
@@ -98,8 +111,8 @@ void string_total_occurrences_of_character_test() {
 }
 
 void string_reverse_test() {
-  string_t string = "hello world";
+  string_t string = string_copy("hello world");
-  string = string_reverse(string);
+  string_reverse(string);
   assert(assert_string_equal(string, "dlrow olleh"));
   free(string);
 }
@@ -157,12 +170,14 @@ void string_join_test() {
 }
 
 void string_concatenate_test() {
-  char* result = string_concatenate("abc", "def");
+  string_t result = string_copy("abc");
+  string_concatenate(&result, "def");
   assert(assert_string_equal(result, "abcdef"));
   free(result);
 
-  result = string_concatenate("abc", "  defghi");
+  result = string_copy("abcz");
-  assert(assert_string_equal(result, "abc  defghi"));
+  string_concatenate(&result, "  defghi");
+  assert(assert_string_equal(result, "abcz  defghi"));
   free(result);
 }
 
@@ -192,7 +207,7 @@ void string_get_is_substring_test() {
 }
 
 void string_get_formatted_number_test() {
-  char* result = string_get_formatted_number(1000, " ");
+  string_t result = string_get_formatted_number(1000, " ");
   assert(assert_string_equal(result, "1 000"));
   free(result);
 
@@ -224,7 +239,7 @@ void string_get_formatted_number_test() {
 void string_get_last_occurence_of_character_test() {
   string_t string = "abcdef";
 
-  char* result = string_get_last_occurence_of_character(string, 'a');
+  string_t result = string_get_last_occurence_of_character(string, 'a');
   assert(assert_string_equal(result, "abcdef"));
   free(result);
 
@@ -266,3 +281,55 @@ void string_ends_with_test() {
   assert(!string_ends_with("abcdef", "bcd"));
   assert(!string_ends_with("abcdef", "abcdefg"));
 }
+
+void string_position_of_test() {
+  assert(string_position_of("hello world", 'e') == 2);
+  assert(string_position_of("hello world", 'o') == 5);
+  assert(string_position_of("abcdef", 'a') == 1);
+  assert(string_position_of("abcdef", 'b') == 2);
+  assert(string_position_of("abcdef", 'c') == 3);
+  assert(string_position_of("abcdef", 'd') == 4);
+  assert(string_position_of("abcdef", 'e') == 5);
+  assert(string_position_of("abcdef", 'f') == 6);
+  assert(string_position_of("abcdef", 'g') == 0);
+}
+
+void string_last_position_of_test() {
+  assert(string_last_position_of("hello world", 'e') == 2);
+  assert(string_last_position_of("hello world", 'o') == 8);
+  assert(string_last_position_of("abcdef", 'a') == 1);
+  assert(string_last_position_of("abcdef", 'b') == 2);
+  assert(string_last_position_of("abcdef", 'c') == 3);
+  assert(string_last_position_of("abcdef", 'd') == 4);
+  assert(string_last_position_of("abcdef", 'e') == 5);
+  assert(string_last_position_of("abcdef", 'f') == 6);
+  assert(string_last_position_of("abcdef", 'g') == 0);
+}
+
+void string_pad_start_test() {
+  string_t result = string_pad_start("hello", "ab", 10);
+  assert(assert_string_equal(result, "ababahello"));
+  free(result);
+
+  result = string_pad_start("hello", "ab", 4);
+  assert(assert_string_equal(result, "hell"));
+  free(result);
+
+  result = string_pad_start("hello", "ab", 5);
+  assert(assert_string_equal(result, "hello"));
+  free(result);
+
+  result = string_pad_start("hello", "ab", 6);
+  assert(assert_string_equal(result, "ahello"));
+  free(result);
+}
+
+void string_zero_pad_test() {
+  string_t result = string_zero_pad(1, 2);
+  assert(assert_string_equal(result, "01"));
+  free(result);
+
+  result = string_zero_pad(10, 2);
+  assert(assert_string_equal(result, "10"));
+  free(result);
+}

test/string_test.h

@@ -6,7 +6,6 @@
 #include <stdlib.h>
 
 #include "libcproject.h"
-#include "test.h"
 
 void string_test();
 
@@ -18,6 +17,8 @@ void string_to_lowercase_test();
 
 void string_replace_test();
 
+void string_remove_character_test();
+
 void string_trim_start_test();
 
 void string_trim_end_test();
@@ -56,4 +57,12 @@ void string_starts_with_test();
 
 void string_ends_with_test();
 
+void string_position_of_test();
+
+void string_last_position_of_test();
+
+void string_pad_start_test();
+
+void string_zero_pad_test();
+
 #endif

test/test.h

@@ -1,14 +0,0 @@
-#ifndef __TEST__
-#define __TEST__
-
-#include <stdbool.h>
-#include <stdio.h>
-#include <string.h>
-
-#include "libcproject.h"
-
-bool assert_string_equal(const string_t actual, const string_t expected);
-
-bool assert_string_not_equal(const string_t actual, const string_t expected);
-
-#endif

version.h

@@ -1,4 +1,4 @@
 #ifndef __LIBCPROJECT_VERSION__
-#define __LIBCPROJECT_VERSION__ "3.1.0"
+#define __LIBCPROJECT_VERSION__ "5.1.0"
 
 #endif