chore(release): 4.0.0 [skip ci]

BREAKING CHANGE: Function signature changed

.github/workflows/ci.yml

@@ -12,6 +12,8 @@ jobs:
     steps:
       - uses: 'actions/checkout@v3.5.3'
 
+      - run: 'sudo apt update'
+
       - name: 'Install Build Tools'
         run: 'sudo apt-get install --yes build-essential gcc make clang-format'
 

.github/workflows/release.yml

@@ -21,18 +21,23 @@ jobs:
           git_user_signingkey: true
           git_commit_gpgsign: true
 
+      - run: 'sudo apt update'
+
       - name: 'Install Build Tools'
-        run: 'sudo apt-get install --yes build-essential gcc make clang-format doxygen doxygen-gui doxygen-doc graphviz'
+        run: 'sudo apt-get install --yes build-essential gcc make clang-format'
+
+      - name: 'Install Documentation Tools'
+        run: 'sudo apt-get install --yes doxygen doxygen-gui doxygen-doc graphviz'
 
       - run: 'make set_version'
 
       - name: 'Use Node.js'
-        uses: 'actions/setup-node@v3.6.0'
+        uses: 'actions/setup-node@v3.7.0'
         with:
-          node-version: '18.16.1'
+          node-version: '18.17.0'
 
       - name: 'Install Release Tools'
-        run: 'npm install --save-dev semantic-release@21.0.5 @commitlint/cli@17.6.6 @commitlint/config-conventional@17.6.6 @semantic-release/git@10.0.1 @semantic-release/exec@6.0.3 @saithodev/semantic-release-backmerge@3.2.0 vercel@30.2.3'
+        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: 'rm --force package.json package-lock.json'
 

.gitignore

@@ -6,3 +6,5 @@ documentation
 *.o
 *.a
 node_modules
+package.json
+package-lock.json

Makefile

@@ -1,6 +1,7 @@
 LIBRARY_NAME = libcproject
 CC = gcc
 CC_FLAGS = -Wall -Wextra -Wfloat-equal -Wundef -Werror -std=c17 -pedantic -pedantic-errors -O3 -I./
+CC_SANITIZER_FLAGS = -fsanitize=address -fsanitize=undefined
 LIB = ./build/${LIBRARY_NAME}.a
 LIB_CC_FLAGS = -L. -l:${LIB}
 LIB_SOURCES = $(wildcard lib/*.c)
@@ -31,18 +32,18 @@ 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})
 	mkdir --parents ./bin
-	${CC} ${CC_FLAGS} -o ${TEST_EXECUTABLE} $(addprefix build/, ${TEST_OBJECTS}) ${LIB_CC_FLAGS}
+	${CC} ${CC_FLAGS} ${CC_SANITIZER_FLAGS} -o ${TEST_EXECUTABLE} $(addprefix build/, ${TEST_OBJECTS}) ${LIB_CC_FLAGS}
 	./${TEST_EXECUTABLE} ${ARGS}
 
 .PHONY: lint

README.md

@@ -20,7 +20,7 @@
 
 C is a low-level programming language and we often end up reinventing the wheel as the C standard library (`libc`) is quite small and in my humble opinion, not well designed.
 
-**libcproject** solve this by providing common functions or data structures (`hash_map`, `array_list`, `linked_list`, `queue`, `stack`, etc.) we might need in our C projects.
+**libcproject** solve this by providing common functions or data structures (`hash_map`, `array_list`, `linked_list`, `queue`, `stack`, etc.), we might need in our C projects.
 
 [Online documentation](https://libcproject.vercel.app/).
 
@@ -36,7 +36,10 @@ C is a low-level programming language and we often end up reinventing the wheel
 For example on GNU/Linux Ubuntu:
 
 ```sh
+# Install Build Tools
 sudo apt-get install build-essential gcc make clang-format
+
+# Install Documentation Tools
 sudo apt-get install doxygen doxygen-gui doxygen-doc graphviz
 ```
 
@@ -55,7 +58,14 @@ nm ./build/libcproject.a # to see the symbols
 
 Steps to create a new C project that uses `libcproject`:
 
-### Step 1: Install and Compile `libcproject`
+### Step 1: Create a new project
+
+```sh
+mkdir my-project
+cd my-project
+```
+
+### Step 2: Install and Compile `libcproject` in the project
 
 ```sh
 # Clone the repository
@@ -68,25 +78,10 @@ cd libcproject
 make
 ```
 
-### Step 2: Create a new project
-
-```sh
-mkdir my-project
-cd my-project
-```
-
-### Step 3: Install `libcproject` in the project
-
-```sh
-mkdir libcproject
-cp --recursive <path-to-libcproject> ./ # copy
-# or
-ln -s <path-to-libcproject> ./ # symbolic link
-```
-
-### Step 4: Create a new C file
+### Step 3: Create a new C file
 
 ```sh
+cd ..
 touch main.c
 ```
 
@@ -97,14 +92,14 @@ touch main.c
 #include "libcproject/libcproject.h"
 
 int main() {
-  string_t string_value = "Hello, world!"; // `string_t` is a typedef from `libcproject`
-  printf("%s\n", string_value);
-  printf("string_length = %ld\n", string_get_length(string_value)); // `string_get_length` is a function from `libcproject`
+  string_t string = "Hello, world!"; // `string_t` is a typedef from `libcproject`
+  printf("%s\n", string);
+  printf("string_length = %ld\n", string_get_length(string)); // `string_get_length` is a function from `libcproject`
   return EXIT_SUCCESS;
 }
 ```
 
-### Step 5: Compile your project and link it with the library
+### Step 4: Compile your project and link it with the library
 
 ```sh
 gcc -o ./main ./main.c -L. -l:./libcproject/build/libcproject.a

lib/array_list.c

@@ -37,3 +37,8 @@ void* array_list_get(struct array_list* list, size_t index) {
   }
   return list->data[index];
 }
+
+void array_list_free(struct array_list* list) {
+  free(list->data);
+  free(list);
+}

lib/array_list.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_ARRAY_LIST__
 #define __LIBCPROJECT_ARRAY_LIST__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
@@ -42,4 +43,10 @@ void array_list_remove(struct array_list* list, size_t index);
  */
 void* array_list_get(struct array_list* list, size_t index);
 
+/**
+ * @brief Frees the array list.
+ * @since v3.0.0
+ */
+void array_list_free(struct array_list* list);
+
 #endif

lib/character.c

@@ -1,17 +1,17 @@
 #include "character.h"
 
-void character_append(string_t string_value, const char character) {
-  size_t length = string_get_length(string_value);
-  character_append_at(string_value, character, length);
+void character_append(string_t string, const char character) {
+  size_t length = string_get_length(string);
+  character_append_at(string, character, length);
 }
 
-void character_append_at(string_t string_value, const char character, const size_t index) {
-  size_t length = string_get_length(string_value);
+void character_append_at(string_t string, const char character, const size_t index) {
+  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_value[length + 1] = '\0';
+  string[index] = character;
+  string[length + 1] = '\0';
 }
 
 char character_to_upper(const char character) {

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
+ * @p
  * @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.

lib/convert.c

@@ -1,11 +1,13 @@
 #include "convert.h"
 
 string_t convert_character_to_string(const char character) {
-  string_t string = malloc(sizeof(string) * 2);
+  string_t string = malloc(sizeof(char) * 2);
   if (string == NULL) {
+    perror("Error (convert_character_to_string)");
     exit(EXIT_FAILURE);
   }
-  character_append(string, character);
+  string[0] = character;
+  string[1] = '\0';
   return string;
 }
 
@@ -17,12 +19,12 @@ char convert_digit_to_character(const char digit) {
   return digit + '0';
 }
 
-long long convert_string_to_number(const string_t string_value) {
-  bool is_negative = string_value[0] == '-';
+long long convert_string_to_number(const string_t string) {
+  bool is_negative = string[0] == '-';
   long long 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;
 }
@@ -33,23 +35,31 @@ string_t convert_number_to_string(const long long integer) {
   }
   bool is_negative = integer < 0;
   size_t length = 1;
-  string_t string_value = malloc(sizeof(string_t) * length);
-  if (string_value == NULL) {
-    exit(EXIT_FAILURE);
-  }
   long long current = mathematics_absolute_value(integer);
   while (current != 0) {
-    character_append(string_value, convert_digit_to_character(current % 10));
     current = current / 10;
     length++;
-    string_value = realloc(string_value, sizeof(string_t) * length);
   }
   if (is_negative) {
-    character_append(string_value, '-');
     length++;
-    string_value = realloc(string_value, sizeof(string_t) * length);
   }
-  return string_reverse(string_value);
+  string_t string = malloc(sizeof(char) * length);
+  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[index++] = convert_digit_to_character(current % 10);
+    current = current / 10;
+  }
+  if (is_negative) {
+    string[index++] = '-';
+  }
+  string[index] = '\0';
+  string_reverse(string);
+  return string;
 }
 
 string_t convert_number_from_base_10_to_base(unsigned long long number, unsigned int base) {
@@ -63,7 +73,7 @@ string_t convert_number_from_base_10_to_base(unsigned long long number, unsigned
     number = number / base;
     index++;
   }
-  string_t result = malloc(sizeof(string_t) * (index + 1));
+  string_t result = malloc(sizeof(char) * (index + 1));
   int index_result = 0;
   for (int iteration = index - 1; iteration >= 0; iteration--) {
     int remainder = remainders[iteration];
@@ -74,6 +84,7 @@ string_t convert_number_from_base_10_to_base(unsigned long long number, unsigned
     }
     index_result++;
   }
+  result[index_result] = '\0';
   return result;
 }
 

lib/convert.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_CONVERT__
 #define __LIBCPROJECT_CONVERT__
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -37,10 +38,10 @@ char convert_digit_to_character(const char digit);
 /**
  * @brief Convert a string to a number.
  *
- * @param string_value
+ * @param string
  * @since v1.0.0
  */
-long long convert_string_to_number(const string_t string_value);
+long long convert_string_to_number(const string_t string);
 
 /**
  * @brief Convert a number to a string.

lib/filesystem.c

@@ -27,63 +27,224 @@ int filesystem_write(string_t path, byte_t *file_content, off_t file_size) {
   return 0;
 }
 
+bool filesystem_exists(string_t path) {
+  return access(path, F_OK) == 0;
+}
+
+int filesystem_remove(string_t path) {
+  return remove(path);
+}
+
 string_t filesystem_get_mimetype(string_t path) {
-  if (string_ends_with(path, ".html")) {
-    return "text/html";
+  if (string_ends_with(path, ".aac")) {
+    return "audio/aac";
   }
-  if (string_ends_with(path, ".css")) {
-    return "text/css";
+  if (string_ends_with(path, ".abw")) {
+    return "application/x-abiword";
   }
-  if (string_ends_with(path, ".js")) {
-    return "text/javascript";
+  if (string_ends_with(path, ".arc")) {
+    return "application/x-freearc";
   }
-  if (string_ends_with(path, ".png")) {
-    return "image/png";
+  if (string_ends_with(path, ".avif")) {
+    return "image/avif";
   }
-  if (string_ends_with(path, ".jpg") || string_ends_with(path, ".jpeg")) {
-    return "image/jpeg";
+  if (string_ends_with(path, ".avi")) {
+    return "video/x-msvideo";
   }
-  if (string_ends_with(path, ".gif")) {
-    return "image/gif";
-  }
-  if (string_ends_with(path, ".ico")) {
-    return "image/x-icon";
-  }
-  if (string_ends_with(path, ".svg")) {
-    return "image/svg+xml";
-  }
-  if (string_ends_with(path, ".json")) {
-    return "application/json";
-  }
-  if (string_ends_with(path, ".pdf")) {
-    return "application/pdf";
-  }
-  if (string_ends_with(path, ".xml")) {
-    return "application/xml";
-  }
-  if (string_ends_with(path, ".csv")) {
-    return "text/csv";
-  }
-  if (string_ends_with(path, ".zip")) {
-    return "application/zip";
-  }
-  if (string_ends_with(path, ".tar")) {
-    return "application/x-tar";
-  }
-  if (string_ends_with(path, ".gz")) {
-    return "application/x-gzip";
-  }
-  if (string_ends_with(path, ".mp3")) {
-    return "audio/mpeg";
-  }
-  if (string_ends_with(path, ".wav")) {
-    return "audio/wav";
-  }
-  if (string_ends_with(path, ".mp4")) {
-    return "video/mp4";
+  if (string_ends_with(path, ".azw")) {
+    return "application/vnd.amazon.ebook";
   }
   if (string_ends_with(path, ".bin")) {
     return "application/octet-stream";
   }
+  if (string_ends_with(path, ".bmp")) {
+    return "image/bmp";
+  }
+  if (string_ends_with(path, ".bz")) {
+    return "application/x-bzip";
+  }
+  if (string_ends_with(path, ".bz2")) {
+    return "application/x-bzip2";
+  }
+  if (string_ends_with(path, ".cda")) {
+    return "application/x-cdf";
+  }
+  if (string_ends_with(path, ".csh")) {
+    return "application/x-csh";
+  }
+  if (string_ends_with(path, ".css")) {
+    return "text/css";
+  }
+  if (string_ends_with(path, ".csv")) {
+    return "text/csv";
+  }
+  if (string_ends_with(path, ".doc")) {
+    return "application/msword";
+  }
+  if (string_ends_with(path, ".docx")) {
+    return "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
+  }
+  if (string_ends_with(path, ".eot")) {
+    return "application/vnd.ms-fontobject";
+  }
+  if (string_ends_with(path, ".epub")) {
+    return "application/epub+zip";
+  }
+  if (string_ends_with(path, ".gz")) {
+    return "application/gzip";
+  }
+  if (string_ends_with(path, ".gif")) {
+    return "image/gif";
+  }
+  if (string_ends_with(path, ".htm") || string_ends_with(path, ".html")) {
+    return "text/html";
+  }
+  if (string_ends_with(path, ".ico")) {
+    return "image/vnd.microsoft.icon";
+  }
+  if (string_ends_with(path, ".ics")) {
+    return "text/calendar";
+  }
+  if (string_ends_with(path, ".jar")) {
+    return "application/java-archive";
+  }
+  if (string_ends_with(path, ".jpg") || string_ends_with(path, ".jpeg") || string_ends_with(path, ".jpe") || string_ends_with(path, ".jif") || string_ends_with(path, ".jfif") || string_ends_with(path, ".jfi")) {
+    return "image/jpeg";
+  }
+  if (string_ends_with(path, ".js") || string_ends_with(path, ".mjs") || string_ends_with(path, ".cjs")) {
+    return "text/javascript";
+  }
+  if (string_ends_with(path, ".json")) {
+    return "application/json";
+  }
+  if (string_ends_with(path, ".jsonld")) {
+    return "application/ld+json";
+  }
+  if (string_ends_with(path, ".mid") || string_ends_with(path, ".midi")) {
+    return "audio/midi";
+  }
+  if (string_ends_with(path, ".mp3")) {
+    return "audio/mpeg";
+  }
+  if (string_ends_with(path, ".mp4")) {
+    return "video/mp4";
+  }
+  if (string_ends_with(path, ".mpeg")) {
+    return "video/mpeg";
+  }
+  if (string_ends_with(path, ".mpkg")) {
+    return "application/vnd.apple.installer+xml";
+  }
+  if (string_ends_with(path, ".odp")) {
+    return "application/vnd.oasis.opendocument.presentation";
+  }
+  if (string_ends_with(path, ".ods")) {
+    return "application/vnd.oasis.opendocument.spreadsheet";
+  }
+  if (string_ends_with(path, ".odt")) {
+    return "application/vnd.oasis.opendocument.text";
+  }
+  if (string_ends_with(path, ".oga")) {
+    return "audio/ogg";
+  }
+  if (string_ends_with(path, ".ogv")) {
+    return "video/ogg";
+  }
+  if (string_ends_with(path, ".ogx")) {
+    return "application/ogg";
+  }
+  if (string_ends_with(path, ".opus")) {
+    return "audio/opus";
+  }
+  if (string_ends_with(path, ".otf")) {
+    return "font/otf";
+  }
+  if (string_ends_with(path, ".png")) {
+    return "image/png";
+  }
+  if (string_ends_with(path, ".pdf")) {
+    return "application/pdf";
+  }
+  if (string_ends_with(path, ".php")) {
+    return "application/x-httpd-php";
+  }
+  if (string_ends_with(path, ".ppt")) {
+    return "application/vnd.ms-powerpoint";
+  }
+  if (string_ends_with(path, ".pptx")) {
+    return "application/vnd.openxmlformats-officedocument.presentationml.presentation";
+  }
+  if (string_ends_with(path, ".rar")) {
+    return "application/vnd.rar";
+  }
+  if (string_ends_with(path, ".rtf")) {
+    return "application/rtf";
+  }
+  if (string_ends_with(path, ".sh")) {
+    return "application/x-sh";
+  }
+  if (string_ends_with(path, ".svg")) {
+    return "image/svg+xml";
+  }
+  if (string_ends_with(path, ".tar")) {
+    return "application/x-tar";
+  }
+  if (string_ends_with(path, ".tif") || string_ends_with(path, ".tiff")) {
+    return "image/tiff";
+  }
+  if (string_ends_with(path, ".ts")) {
+    return "application/typescript";
+  }
+  if (string_ends_with(path, ".ttf")) {
+    return "font/ttf";
+  }
+  if (string_ends_with(path, ".txt")) {
     return "text/plain";
+  }
+  if (string_ends_with(path, ".vsd")) {
+    return "application/vnd.visio";
+  }
+  if (string_ends_with(path, ".wav")) {
+    return "audio/wav";
+  }
+  if (string_ends_with(path, ".weba") || string_ends_with(path, ".webm")) {
+    return "audio/webm";
+  }
+  if (string_ends_with(path, ".webp")) {
+    return "image/webp";
+  }
+  if (string_ends_with(path, ".woff")) {
+    return "font/woff";
+  }
+  if (string_ends_with(path, ".woff2")) {
+    return "font/woff2";
+  }
+  if (string_ends_with(path, ".xhtml")) {
+    return "application/xhtml+xml";
+  }
+  if (string_ends_with(path, ".xls")) {
+    return "application/vnd.ms-excel";
+  }
+  if (string_ends_with(path, ".xlsx")) {
+    return "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
+  }
+  if (string_ends_with(path, ".xml")) {
+    return "application/xml";
+  }
+  if (string_ends_with(path, ".xul")) {
+    return "application/vnd.mozilla.xul+xml";
+  }
+  if (string_ends_with(path, ".zip")) {
+    return "application/zip";
+  }
+  if (string_ends_with(path, ".3gp")) {
+    return "video/3gpp";
+  }
+  if (string_ends_with(path, ".3g2")) {
+    return "video/3gpp2";
+  }
+  if (string_ends_with(path, ".7z")) {
+    return "application/x-7z-compressed";
+  }
+  return "application/octet-stream";
 }

lib/filesystem.h

@@ -38,9 +38,32 @@ int filesystem_read(string_t path, byte_t **file_content, off_t *file_size);
 int filesystem_write(string_t path, byte_t *file_content, off_t file_size);
 
 /**
- * @brief Get the mimetype of a file.
+ * @brief Check if a path exists.
  *
  * @param path
+ * @retval true if the path exists.
+ * @retval false if the path does not exist.
+ * @since v3.1.0
+ */
+bool filesystem_exists(string_t path);
+
+/**
+ * @brief Removes a path.
+ *
+ * @param path
+ * @return int
+ * @retval -1 if there is an error.
+ * @retval 0 for success.
+ * @since v3.1.0
+ */
+int filesystem_remove(string_t path);
+
+/**
+ * @brief Get the mimetype of a file based on its extension.
+ *
+ * @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
  * @since v1.0.0
  */
 string_t filesystem_get_mimetype(string_t path);

lib/hash_map.c

@@ -2,31 +2,7 @@
 
 #define ROTATE_LEFT(x, b) (((x) << (b)) | ((x) >> (64 - (b))))
 
-uint64_t hash(string_t key, size_t capacity) {
-  size_t key_length = string_get_length(key);
-  const uint64_t c = 0x736f6d6570736575;
-  uint64_t v0 = 0x736f6d6570736575 ^ c;
-  uint64_t v1 = 0x646f72616e646f6d ^ c;
-  uint64_t v2 = 0x6c7967656e657261 ^ c;
-  uint64_t v3 = 0x7465646279746573 ^ c;
-  uint64_t k1;
-  uint64_t m;
-  uint8_t *message = (uint8_t *)key;
-  size_t remaining = key_length;
-  uint64_t hash;
-
-  message += sizeof(uint64_t);
-  k1 = *(uint64_t *)message;
-
-  if (key_length % sizeof(uint64_t) != 0) {
-    memcpy(&k1, key + (key_length - sizeof(uint64_t)), sizeof(uint64_t));
-  }
-
-  while (remaining >= 8) {
-    memcpy(&m, message, sizeof(uint64_t));
-    v3 ^= m;
-
-    for (int i = 0; i < 2; i++) {
+uint64_t sip_round(uint64_t v0, uint64_t v1, uint64_t v2, uint64_t v3) {
   v0 += v1;
   v2 += v3;
   v1 = ROTATE_LEFT(v1, 13);
@@ -41,36 +17,72 @@ uint64_t hash(string_t key, size_t capacity) {
   v1 ^= v2;
   v3 ^= v0;
   v2 = ROTATE_LEFT(v2, 32);
+  return v0;
+}
+
+uint64_t hash(string_t key, size_t capacity) {
+  size_t key_length = string_get_length(key);
+  const uint64_t c = 0x736f6d6570736575;
+  uint64_t v0 = c ^ 0x736f6d6570736575;
+  uint64_t v1 = c ^ 0x646f72616e646f6d;
+  uint64_t v2 = c ^ 0x6c7967656e657261;
+  uint64_t v3 = c ^ 0x7465646279746573;
+
+  uint64_t m;
+  uint64_t hash;
+
+  uint8_t *message = (uint8_t *)key;
+
+  size_t remaining = key_length;
+  size_t offset = 0;
+
+  while (remaining >= 8) {
+    memcpy(&m, message + offset, sizeof(uint64_t));
+    v3 ^= m;
+
+    for (int i = 0; i < 2; i++) {
+      v0 = sip_round(v0, v1, v2, v3);
+      v1 = ROTATE_LEFT(v1, 13);
+      v2 = ROTATE_LEFT(v2, 16);
+      v3 = ROTATE_LEFT(v3, 32);
+      v0 ^= m;
     }
 
-    v0 ^= m;
+    v2 ^= 0xff;
+    for (int i = 0; i < 4; i++) {
+      v0 = sip_round(v0, v1, v2, v3);
+      v1 = ROTATE_LEFT(v1, 13);
+      v2 = ROTATE_LEFT(v2, 16);
+      v3 = ROTATE_LEFT(v3, 32);
+    }
+
+    hash = v0 ^ v1 ^ v2 ^ v3;
     remaining -= sizeof(uint64_t);
-    message += sizeof(uint64_t);
+    offset += sizeof(uint64_t);
   }
 
   m = (uint64_t)remaining << 56;
-
   switch (remaining) {
     case 7:
-      m |= (uint64_t)message[6] << 48;
+      m |= (uint64_t)message[offset + 6] << 48;
       break;
     case 6:
-      m |= (uint64_t)message[5] << 40;
+      m |= (uint64_t)message[offset + 5] << 40;
       break;
     case 5:
-      m |= (uint64_t)message[4] << 32;
+      m |= (uint64_t)message[offset + 4] << 32;
       break;
     case 4:
-      m |= (uint64_t)message[3] << 24;
+      m |= (uint64_t)message[offset + 3] << 24;
       break;
     case 3:
-      m |= (uint64_t)message[2] << 16;
+      m |= (uint64_t)message[offset + 2] << 16;
       break;
     case 2:
-      m |= (uint64_t)message[1] << 8;
+      m |= (uint64_t)message[offset + 1] << 8;
       break;
     case 1:
-      m |= (uint64_t)message[0];
+      m |= (uint64_t)message[offset];
       break;
     default:
       break;
@@ -79,40 +91,20 @@ uint64_t hash(string_t key, size_t capacity) {
   v3 ^= m;
 
   for (int i = 0; i < 2; i++) {
-    v0 += v1;
-    v2 += v3;
+    v0 = sip_round(v0, v1, v2, v3);
     v1 = ROTATE_LEFT(v1, 13);
-    v3 = ROTATE_LEFT(v3, 16);
-    v1 ^= v0;
-    v3 ^= v2;
-    v0 = ROTATE_LEFT(v0, 32);
-    v2 += v1;
-    v0 += v3;
-    v1 = ROTATE_LEFT(v1, 17);
-    v3 = ROTATE_LEFT(v3, 21);
-    v1 ^= v2;
-    v3 ^= v0;
-    v2 = ROTATE_LEFT(v2, 32);
+    v2 = ROTATE_LEFT(v2, 16);
+    v3 = ROTATE_LEFT(v3, 32);
   }
 
   v0 ^= m;
   v2 ^= 0xff;
 
   for (int i = 0; i < 4; i++) {
-    v0 += v1;
-    v2 += v3;
+    v0 = sip_round(v0, v1, v2, v3);
     v1 = ROTATE_LEFT(v1, 13);
-    v3 = ROTATE_LEFT(v3, 16);
-    v1 ^= v0;
-    v3 ^= v2;
-    v0 = ROTATE_LEFT(v0, 32);
-    v2 += v1;
-    v0 += v3;
-    v1 = ROTATE_LEFT(v1, 17);
-    v3 = ROTATE_LEFT(v3, 21);
-    v1 ^= v2;
-    v3 ^= v0;
-    v2 = ROTATE_LEFT(v2, 32);
+    v2 = ROTATE_LEFT(v2, 16);
+    v3 = ROTATE_LEFT(v3, 32);
   }
 
   hash = v0 ^ v1 ^ v2 ^ v3;
@@ -131,7 +123,7 @@ struct hash_map *hash_map_initialization() {
   return hash_map;
 }
 
-void hash_map_add(struct hash_map *hash_map, string_t key, void *data) {
+void hash_map_add(struct hash_map *hash_map, string_t key_value, void *data) {
   if (hash_map->length == hash_map->capacity) {
     size_t previous_capacity = hash_map->capacity;
     hash_map->capacity += HASH_MAP_INITIAL_CAPACITY;
@@ -140,6 +132,7 @@ void hash_map_add(struct hash_map *hash_map, string_t key, void *data) {
       hash_map->items[index] = NULL;
     }
   }
+  string_t key = string_copy(key_value);
   uint64_t hash_value = hash(key, hash_map->capacity);
   struct linked_list *list = hash_map->items[hash_value];
   struct hash_map_item *item = malloc(sizeof(struct hash_map_item));
@@ -164,6 +157,9 @@ void hash_map_add(struct hash_map *hash_map, string_t key, void *data) {
     if (!found) {
       linked_list_add_in_head(list, (void *)item);
       hash_map->length++;
+    } else {
+      free(key);
+      free(item);
     }
   }
 }
@@ -180,10 +176,13 @@ void hash_map_remove(struct hash_map *hash_map, string_t key) {
     struct hash_map_item *item = (struct hash_map_item *)node->data;
     if (!string_equals(key, item->key)) {
       linked_list_add_in_head(new_list, item);
+    } else {
+      free(item->key);
+      free(item);
     }
     node = node->next;
   }
-  free(list);
+  linked_list_free(list);
   hash_map->items[hash_value] = new_list;
   hash_map->length--;
 }
@@ -225,3 +224,21 @@ string_t *hash_map_get_keys(struct hash_map *hash_map) {
   }
   return keys;
 }
+
+void hash_map_free(struct hash_map *hash_map) {
+  for (size_t index = 0; index < hash_map->capacity; index++) {
+    struct linked_list *list = hash_map->items[index];
+    if (list != NULL) {
+      struct linked_list_node *node = list->head;
+      while (node != NULL) {
+        struct hash_map_item *item = (struct hash_map_item *)node->data;
+        free(item->key);
+        free(item);
+        node = node->next;
+      }
+      linked_list_free(list);
+    }
+  }
+  free(hash_map->items);
+  free(hash_map);
+}

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>
@@ -89,4 +90,10 @@ bool hash_map_contains_key(struct hash_map *hash_map, string_t key);
  */
 string_t *hash_map_get_keys(struct hash_map *hash_map);
 
+/**
+ * @brief Frees the hash map.
+ * @since v3.0.0
+ */
+void hash_map_free(struct hash_map *hash_map);
+
 #endif

lib/linked_list.c

@@ -3,6 +3,7 @@
 struct linked_list *linked_list_initialization() {
   struct linked_list *list = malloc(sizeof(*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) {
+  if (list == NULL) {
+    errno = EINVAL;
+    perror("Error (linked_list_add_in_head)");
+    exit(EXIT_FAILURE);
+  }
   struct linked_list_node *node_new = malloc(sizeof(*node_new));
-  if (list == NULL || node_new == NULL) {
+  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));
-  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;
@@ -68,6 +83,7 @@ struct linked_list *linked_list_reverse(struct linked_list *list) {
     linked_list_add_after_last(linked_list_reversed, stack_node_current->data);
     stack_node_current = stack_node_current->next;
   }
+  stack_free(stack);
   return linked_list_reversed;
 }
 
@@ -84,3 +100,14 @@ void linked_list_reverse_mutate(struct linked_list *list) {
     (*current) = temporary_current;
   }
 }
+
+void linked_list_free(struct linked_list *list) {
+  struct linked_list_node *node_current = list->head;
+  while (node_current != NULL) {
+    struct linked_list_node *node_to_remove = node_current;
+    node_current = node_current->next;
+    free(node_to_remove);
+  }
+  list->head = NULL;
+  free(list);
+}

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>
 
@@ -62,4 +63,10 @@ struct linked_list *linked_list_reverse(struct linked_list *list);
  */
 void linked_list_reverse_mutate(struct linked_list *list);
 
+/**
+ * @brief Frees the linked list.
+ * @since v3.0.0
+ */
+void linked_list_free(struct linked_list *list);
+
 #endif

lib/mathematics.h

@@ -3,6 +3,7 @@
 
 #define MATHEMATICS_FLOAT_PRECISION 0.00000001
 
+#include <errno.h>
 #include <stdbool.h>
 
 #include "types.h"

lib/queue.c

@@ -3,6 +3,7 @@
 struct queue *queue_initialization() {
   struct queue *queue = malloc(sizeof(*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) {
+  if (queue == NULL) {
+    errno = EINVAL;
+    perror("Error (queue_push)");
+    exit(EXIT_FAILURE);
+  }
   struct queue_node *node_new = malloc(sizeof(*node_new));
-  if (queue == NULL || node_new == NULL) {
+  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;
@@ -43,3 +52,18 @@ void *queue_pop(struct queue *queue) {
   queue->length = queue->length - 1;
   return data;
 }
+
+void queue_free(struct queue *queue) {
+  if (queue == NULL) {
+    errno = EINVAL;
+    perror("Error (queue_free)");
+    exit(EXIT_FAILURE);
+  }
+  struct queue_node *node = queue->first;
+  while (node != NULL) {
+    struct queue_node *node_next = node->next;
+    free(node);
+    node = node_next;
+  }
+  free(queue);
+}

lib/queue.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_QUEUE__
 #define __LIBCPROJECT_QUEUE__
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -42,4 +43,10 @@ void queue_push(struct queue *queue, void *data);
  */
 void *queue_pop(struct queue *queue);
 
+/**
+ * @brief Frees the queue.
+ * @since v3.0.0
+ */
+void queue_free(struct queue *queue);
+
 #endif

lib/stack.c

@@ -3,6 +3,7 @@
 struct stack *stack_initialization() {
   struct stack *stack = malloc(sizeof(*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) {
+  if (stack == NULL) {
+    errno = EINVAL;
+    perror("Error (stack_push)");
+    exit(EXIT_FAILURE);
+  }
   struct stack_node *node_new = malloc(sizeof(*node_new));
-  if (stack == NULL || data == NULL) {
+  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;
@@ -35,3 +44,18 @@ void *stack_pop(struct stack *stack) {
   stack->length = stack->length - 1;
   return data;
 }
+
+void stack_free(struct stack *stack) {
+  if (stack == NULL) {
+    errno = EINVAL;
+    perror("Error (stack_free)");
+    exit(EXIT_FAILURE);
+  }
+  struct stack_node *node = stack->first;
+  while (node != NULL) {
+    struct stack_node *node_next = node->next;
+    free(node);
+    node = node_next;
+  }
+  free(stack);
+}

lib/stack.h

@@ -1,6 +1,7 @@
 #ifndef __LIBCPROJECT_STACK__
 #define __LIBCPROJECT_STACK__
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -42,4 +43,10 @@ void stack_push(struct stack *stack, void *data);
  */
 void *stack_pop(struct stack *stack);
 
+/**
+ * @brief Frees the stack.
+ * @since v3.0.0
+ */
+void stack_free(struct stack *stack);
+
 #endif

lib/string.c

@@ -1,118 +1,96 @@
 #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) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
+void string_to_uppercase(string_t string) {
+  size_t string_length = string_get_length(string);
   for (size_t index = 0; index < string_length; index++) {
-    character_append(result, character_to_upper(string_value[index]));
+    string[index] = character_to_upper(string[index]);
   }
-  return result;
+  string[string_length] = '\0';
 }
 
-string_t string_to_lowercase(string_t string_value) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
+void string_to_lowercase(string_t string) {
+  size_t string_length = string_get_length(string);
   for (size_t index = 0; index < string_length; index++) {
-    character_append(result, character_to_lower(string_value[index]));
+    string[index] = character_to_lower(string[index]);
   }
-  return result;
+  string[string_length] = '\0';
 }
 
-string_t string_replace(string_t string_value, char search, char replace) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
+void string_replace(string_t string, char search, char replace) {
+  size_t string_length = string_get_length(string);
   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) {
-      character_append(result, replace);
+      string[index] = replace;
     } else {
-      character_append(result, string_value[index]);
+      string[index] = string[index];
     }
   }
-  return result;
+  string[string_length] = '\0';
 }
 
-string_t string_trim_start(string_t string_value) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
+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] == ' ') {
+  while (string[index_space] == character) {
     index_space++;
   }
-  for (size_t index = index_space; index < string_length; index++) {
-    character_append(result, string_value[index]);
+  for (size_t index = 0; index < string_length - index_space; index++) {
+    string[index] = string[index + index_space];
   }
-  return result;
+  string[string_length - index_space] = '\0';
 }
 
-string_t string_trim_end(string_t string_value) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
-  }
+void string_trim_end(string_t string, char character) {
+  size_t string_length = string_get_length(string);
   size_t index_space = string_length - 1;
-  while (string_value[index_space] == ' ') {
+  while (string[index_space] == character) {
     index_space--;
   }
-  for (size_t index = 0; index < index_space + 1; index++) {
-    character_append(result, string_value[index]);
-  }
-  return result;
+  string[index_space + 1] = '\0';
 }
 
-string_t string_trim(string_t string_value) {
-  string_t result = string_trim_start(string_value);
-  result = string_trim_end(result);
-  return result;
+void string_trim(string_t string, char character) {
+  string_trim_start(string, character);
+  string_trim_end(string, character);
 }
 
-string_t string_copy(const string_t string_value) {
-  return string_substring(string_value, 0, string_get_length(string_value));
-}
-
-string_t string_capitalize(string_t string_value) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
+string_t string_copy(const string_t string) {
+  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);
   }
-  for (size_t index = 0; index < string_length; index++) {
-    bool is_first_character = index == 0;
-    if (is_first_character) {
-      character_append(result, character_to_upper(string_value[index]));
-    } else {
-      character_append(result, string_value[index]);
+  size_t index;
+  for (index = 0; index < source_length; index++) {
+    copy[index] = string[index];
   }
-  }
-  return result;
+  copy[index] = '\0';
+  return copy;
 }
 
-size_t string_total_occurrences_of_character(string_t string_value, char character) {
+void string_capitalize(string_t string) {
+  size_t string_length = string_get_length(string);
+  if (string_length == 0) {
+    return;
+  }
+  string[0] = character_to_upper(string[0]);
+}
+
+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;
     }
@@ -120,18 +98,17 @@ size_t string_total_occurrences_of_character(string_t string_value, char charact
   return result;
 }
 
-string_t string_reverse(const string_t string_value) {
-  size_t string_length = string_get_length(string_value);
-  size_t index = 0;
-  string_t result = malloc(sizeof(string_t) * string_length);
-  if (result == NULL) {
-    exit(EXIT_FAILURE);
+void string_reverse(const string_t string) {
+  size_t string_length = string_get_length(string);
+  size_t index_start = 0;
+  size_t index_end = string_length - 1;
+  while (index_start < index_end) {
+    char temporary = string[index_start];
+    string[index_start] = string[index_end];
+    string[index_end] = temporary;
+    index_start++;
+    index_end--;
   }
-  for (index = string_length - 1; index > 0; index--) {
-    character_append(result, string_value[index]);
-  }
-  character_append(result, string_value[index]);
-  return result;
 }
 
 bool string_equals(const string_t string1, const string_t string2) {
@@ -146,11 +123,11 @@ 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 {
@@ -158,7 +135,7 @@ 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++;
@@ -166,32 +143,40 @@ 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) {
-  size_t string_length = string_get_length(string_value);
+string_t* string_split(const string_t string, char separator, size_t* result_size) {
+  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(string_t) * string_length);
-  string_t* result = malloc(sizeof(string_t*) * index_result);
-  if (result == NULL || current == NULL) {
+  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) {
-      result[index_result] = string_copy(current);
-      index_result++;
-      result = realloc(result, sizeof(string_value) * index_result);
+    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;
-      current = string_copy("");
     } else {
-      character_append(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);
   free(current);
   *result_size = index_result + 1;
@@ -199,80 +184,96 @@ string_t* string_split(const string_t string_value, char separator, size_t* resu
 }
 
 string_t string_join(string_t* array, const char separator, size_t array_length) {
-  size_t string_length = array_length;
-  string_t string_value = malloc(sizeof(string_value) * string_length);
-  if (string_value == NULL) {
+  size_t total_length = 0;
+  for (size_t index_array = 0; index_array < array_length; index_array++) {
+    total_length += string_get_length(array[index_array]);
+  }
+  size_t string_length = total_length + (array_length - 1);
+  string_t string = malloc(sizeof(char) * (string_length + 1));
+  if (string == NULL) {
+    perror("Error (string_join)");
     exit(EXIT_FAILURE);
   }
+  size_t current_index = 0;
   for (size_t index_array = 0; index_array < array_length; index_array++) {
     string_t substring = array[index_array];
     size_t substring_length = string_get_length(substring);
-    string_length += substring_length;
-    string_value = realloc(string_value, sizeof(string_value) * string_length);
-    if (string_value == NULL) {
-      exit(EXIT_FAILURE);
-    }
     for (size_t index_substring = 0; index_substring < substring_length; index_substring++) {
-      character_append(string_value, substring[index_substring]);
+      string[current_index] = substring[index_substring];
+      current_index++;
     }
     bool is_last_character = index_array == (array_length - 1);
     if (!is_last_character) {
-      character_append(string_value, separator);
+      string[current_index] = separator;
+      current_index++;
     }
   }
-  return string_value;
+  string[string_length] = '\0';
+  return string;
 }
 
-string_t string_concatenate(string_t string1, string_t string2) {
-  size_t string1_length = string_get_length(string1);
-  size_t string2_length = string_get_length(string2);
-  size_t result_length = string1_length + string2_length;
-  string_t result = malloc(sizeof(string_t) * result_length);
-  if (result == NULL) {
+void string_concatenate(string_t* destination, string_t source) {
+  size_t destination_length = string_get_length(*destination);
+  size_t source_length = string_get_length(source);
+  size_t new_length = destination_length + source_length;
+  *destination = realloc(*destination, sizeof(char) * (new_length + 1));
+  if (*destination == NULL) {
+    perror("Error (string_concatenate)");
     exit(EXIT_FAILURE);
   }
-  for (size_t index_string1 = 0; index_string1 < string1_length; index_string1++) {
-    character_append(result, string1[index_string1]);
+  size_t index_destination = destination_length;
+  for (size_t index_source = 0; index_source < source_length; index_source++) {
+    (*destination)[index_destination++] = source[index_source];
   }
-  for (size_t index_string2 = 0; index_string2 < string2_length; index_string2++) {
-    character_append(result, string2[index_string2]);
-  }
-  return result;
+  (*destination)[index_destination] = '\0';
 }
 
-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];
-    string_t key = convert_character_to_string(character);
+    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)) {
       has_unique = false;
     } else {
       hash_map_add(characters_already_seen, key, (void*)true);
     }
   }
+  for (size_t index = 0; index < string_length; index++) {
+    if (keys[index] != NULL) {
+      free(keys[index]);
+    }
+  }
+  free(keys);
+  hash_map_free(characters_already_seen);
   return has_unique;
 }
 
-string_t string_substring(const string_t string_value, size_t index_start, size_t index_end) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
-  for (size_t index = index_start; index <= index_end; index++) {
-    character_append(result, string_value[index]);
+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[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++;
     }
@@ -282,72 +283,88 @@ bool string_get_is_substring(const string_t string_value, const string_t substri
 }
 
 string_t string_get_formatted_number(const long long number, string_t separator) {
-  string_t number_string = convert_number_to_string(number);
-  bool is_negative = number_string[0] == '-';
+  string_t number_string_temp = convert_number_to_string(number);
+  string_t number_string = number_string_temp;
+  bool is_negative = number_string_temp[0] == '-';
   if (is_negative) {
-    number_string = string_substring(number_string, 1, string_get_length(number_string));
+    number_string = string_substring(number_string_temp, 1, string_get_length(number_string_temp));
+    free(number_string_temp);
   }
   size_t number_string_length = string_get_length(number_string);
-  string_t result = malloc(sizeof(string_t) * number_string_length);
+  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;
+  size_t result_index = 0;
   for (size_t index = 0; index < number_string_length; index++) {
     size_t index_reversed = number_string_length - index - 1;
+    result[result_index] = number_string[index_reversed];
     count++;
-    result = string_concatenate(result, convert_character_to_string(number_string[index_reversed]));
-    if (count == 3) {
-      result = string_concatenate(result, separator);
+    result_index++;
+    if (count == 3 && index != number_string_length - 1) {
+      for (size_t sep_index = 0; sep_index < string_get_length(separator); sep_index++) {
+        result[result_index] = separator[sep_index];
+        result_index++;
+      }
       count = 0;
     }
   }
-  result = string_reverse(result);
-  size_t result_length = string_get_length(result);
-  if (result_length % 4 == 0) {
-    result = string_substring(result, 1, result_length);
-  }
+  free(number_string);
+  result[formatted_length] = '\0';
+  string_reverse(result);
   if (is_negative) {
-    result = string_concatenate(convert_character_to_string('-'), result);
+    string_t negative_result = convert_character_to_string('-');
+    string_concatenate(&negative_result, result);
+    free(result);
+    return negative_result;
   }
   return result;
 }
 
-string_t string_get_last_occurence_of_character(const string_t string_value, char character) {
-  size_t string_length = string_get_length(string_value);
-  string_t result = malloc(sizeof(string_t) * string_length);
+string_t string_get_last_occurence_of_character(const string_t string, char character) {
+  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[index] == character) {
+      index_last_occurrence = index;
+    }
+  }
+  if (index_last_occurrence == SIZE_MAX) {
+    return "";
+  }
+  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 = 0; index < string_length; index++) {
-    if (string_value[index] == character) {
-      index_result = 0;
-      result = string_copy("");
-    }
-    character_append(result, string_value[index]);
-    index_result++;
+  for (size_t index = index_last_occurrence; index < string_length; 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--;
   }

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>
@@ -13,93 +14,109 @@
 /**
  * @brief Return the length of a string (excluding '\0').
  *
- * @param string_value
+ * @param string
  * @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 whitespace from the start of a string.
+ * @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);
+void string_trim_start(string_t string, char character);
 
 /**
- * @brief Removes all whitespace from the end of a string.
+ * @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);
+void string_trim_end(string_t string, char character);
 
 /**
- * @brief Removes all whitespace from the start and end of a string.
+ * @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);
+void string_trim(string_t string, char character);
 
 /**
  * @brief Return the copy of a string.
  *
- * @param string_value
+ * @param string
  * @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
  * @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.
@@ -114,21 +131,21 @@ bool string_equals(const string_t string1, const string_t string2);
 /**
  * @brief Check if the string is a integer.
  *
- * @param string_value
+ * @param string
  * @return true if the string is a integer, false otherwise.
  * @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
  * @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.
@@ -143,11 +160,13 @@ string_t string_join(string_t* array, const char separator, size_t array_length)
 /**
  * @brief Concatenate two strings.
  *
- * @param string1
- * @param string2
+ * NOTE: Mutates the string `destination`.
+ *
+ * @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.
@@ -161,22 +180,22 @@ 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
  * @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.
  * @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.
@@ -194,30 +213,30 @@ string_t string_get_formatted_number(const long long number, string_t separator)
 /**
  * @brief Returns a pointer to the last occurrence of character in the string.
  *
- * @param string_value
+ * @param string
  * @param character
  * @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.
  * @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.
  * @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);
 
 #endif

lib/terminal.c

@@ -3,20 +3,22 @@
 string_t terminal_input() {
   char character;
   size_t length = 1;
-  string_t string_value = malloc(length * sizeof(char));
-  if (string_value == NULL) {
+  string_t string = malloc(length * sizeof(char));
+  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));
-    if (string_value == NULL) {
+    string = realloc(string, length * sizeof(char));
+    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*)) {
@@ -54,6 +56,8 @@ void terminal_print_string(void* 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;
@@ -68,6 +72,8 @@ 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;
@@ -82,6 +88,8 @@ 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;
@@ -96,6 +104,8 @@ 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");
@@ -111,3 +121,7 @@ void terminal_print_hash_map(struct hash_map* hash_map, void (*print_element)(vo
   }
   printf("}\n");
 }
+
+void terminal_print_array_list(struct array_list* list, void (*print_element)(void*)) {
+  terminal_print_array(list->data, list->size, sizeof(void*), print_element);
+}

lib/terminal.h

@@ -1,11 +1,13 @@
 #ifndef __LIBCPROJECT_TERMINAL__
 #define __LIBCPROJECT_TERMINAL__
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 
+#include "array_list.h"
 #include "character.h"
 #include "hash_map.h"
 #include "linked_list.h"
@@ -106,4 +108,13 @@ 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*));
 
+/**
+ * @brief Print an array list.
+ *
+ * @param array_list
+ * @param print_element
+ * @since v3.0.0
+ */
+void terminal_print_array_list(struct array_list* list, void (*print_element)(void*));
+
 #endif

main.c

@@ -4,8 +4,8 @@
 #include "libcproject.h"
 
 int main() {
-  string_t string_value = "Hello, world!";
-  printf("%s\n", string_value);
-  printf("string_length = %ld\n", string_get_length(string_value));
+  string_t string = "Hello, world!";
+  printf("%s\n", string);
+  printf("string_length = %ld\n", string_get_length(string));
   return EXIT_SUCCESS;
 }

set_version.c

@@ -3,21 +3,22 @@
 
 #include "libcproject.h"
 
-int main(int argc, string_t* argv) {
+int main(int argc, char** argv) {
   if (argc != 2) {
     fprintf(stderr, "Usage: %s <version>\n", argv[0]);
     return EXIT_FAILURE;
   }
-  string_t content = "#ifndef __LIBCPROJECT_VERSION__\n";
-  content = string_concatenate(content, "#define __LIBCPROJECT_VERSION__ \"");
-  content = string_concatenate(content, argv[1]);
-  content = string_concatenate(content, "\"\n\n");
-  content = string_concatenate(content, "#endif\n");
+  string_t content = string_copy("#ifndef __LIBCPROJECT_VERSION__\n");
+  string_concatenate(&content, "#define __LIBCPROJECT_VERSION__ \"");
+  string_concatenate(&content, argv[1]);
+  string_concatenate(&content, "\"\n\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");
     return EXIT_FAILURE;
   }
   printf("Success: Version set to %s.\n", argv[1]);
+  free(content);
   return EXIT_SUCCESS;
 }

test/array_list_test.c

@@ -32,4 +32,6 @@ void array_list_test() {
   array_list_remove(list, 100);
   assert(list->size == 105);
   assert(array_list_get(list, 100) == (void *)95);
+
+  array_list_free(list);
 }

test/character_test.c

@@ -20,7 +20,7 @@ void character_append_at_test() {
   character_append_at(string, 'd', 1);
   assert(assert_string_equal(string, "adbc"));
 
-  char string2[5] = "abcd";
+  char string2[6] = "abcd";
   character_append_at(string2, 'e', 4);
   assert(assert_string_equal(string2, "abcde"));
 }

test/convert_test.c

@@ -10,11 +10,25 @@ void convert_test() {
 }
 
 void convert_character_to_string_test() {
-  assert(assert_string_equal(convert_character_to_string('a'), "a"));
-  assert(assert_string_equal(convert_character_to_string('A'), "A"));
-  assert(assert_string_equal(convert_character_to_string('0'), "0"));
-  assert(assert_string_equal(convert_character_to_string(' '), " "));
-  assert(assert_string_equal(convert_character_to_string('\0'), ""));
+  char* result = convert_character_to_string('a');
+  assert(assert_string_equal(result, "a"));
+  free(result);
+
+  result = convert_character_to_string('A');
+  assert(assert_string_equal(result, "A"));
+  free(result);
+
+  result = convert_character_to_string('0');
+  assert(assert_string_equal(result, "0"));
+  free(result);
+
+  result = convert_character_to_string(' ');
+  assert(assert_string_equal(result, " "));
+  free(result);
+
+  result = convert_character_to_string('\0');
+  assert(assert_string_equal(result, ""));
+  free(result);
 }
 
 void convert_character_to_digit_test() {
@@ -63,33 +77,109 @@ void convert_string_to_number_test() {
 }
 
 void convert_number_to_string_test() {
-  assert(assert_string_equal(convert_number_to_string(0), "0"));
-  assert(assert_string_equal(convert_number_to_string(1), "1"));
-  assert(assert_string_equal(convert_number_to_string(2), "2"));
-  assert(assert_string_equal(convert_number_to_string(3), "3"));
-  assert(assert_string_equal(convert_number_to_string(4), "4"));
-  assert(assert_string_equal(convert_number_to_string(5), "5"));
-  assert(assert_string_equal(convert_number_to_string(6), "6"));
-  assert(assert_string_equal(convert_number_to_string(7), "7"));
-  assert(assert_string_equal(convert_number_to_string(8), "8"));
-  assert(assert_string_equal(convert_number_to_string(9), "9"));
-  assert(assert_string_equal(convert_number_to_string(10), "10"));
-  assert(assert_string_equal(convert_number_to_string(11), "11"));
-  assert(assert_string_equal(convert_number_to_string(20), "20"));
-  assert(assert_string_equal(convert_number_to_string(-0), "0"));
-  assert(assert_string_equal(convert_number_to_string(-1), "-1"));
-  assert(assert_string_equal(convert_number_to_string(-20), "-20"));
+  char* result = convert_number_to_string(0);
+  assert(assert_string_equal(result, "0"));
+  free(result);
+
+  result = convert_number_to_string(1);
+  assert(assert_string_equal(result, "1"));
+  free(result);
+
+  result = convert_number_to_string(2);
+  assert(assert_string_equal(result, "2"));
+  free(result);
+
+  result = convert_number_to_string(3);
+  assert(assert_string_equal(result, "3"));
+  free(result);
+
+  result = convert_number_to_string(4);
+  assert(assert_string_equal(result, "4"));
+  free(result);
+
+  result = convert_number_to_string(5);
+  assert(assert_string_equal(result, "5"));
+  free(result);
+
+  result = convert_number_to_string(6);
+  assert(assert_string_equal(result, "6"));
+  free(result);
+
+  result = convert_number_to_string(7);
+  assert(assert_string_equal(result, "7"));
+  free(result);
+
+  result = convert_number_to_string(8);
+  assert(assert_string_equal(result, "8"));
+  free(result);
+
+  result = convert_number_to_string(9);
+  assert(assert_string_equal(result, "9"));
+  free(result);
+
+  result = convert_number_to_string(10);
+  assert(assert_string_equal(result, "10"));
+  free(result);
+
+  result = convert_number_to_string(11);
+  assert(assert_string_equal(result, "11"));
+  free(result);
+
+  result = convert_number_to_string(20);
+  assert(assert_string_equal(result, "20"));
+  free(result);
+
+  result = convert_number_to_string(-0);
+  assert(assert_string_equal(result, "0"));
+  free(result);
+
+  result = convert_number_to_string(-1);
+  assert(assert_string_equal(result, "-1"));
+  free(result);
+
+  result = convert_number_to_string(-20);
+  assert(assert_string_equal(result, "-20"));
+  free(result);
 }
 
 void convert_number_from_base_to_another_test() {
-  assert(assert_string_equal(convert_number_from_base_to_another("15", 10, 16), "F"));
-  assert(assert_string_equal(convert_number_from_base_to_another("100000000", 2, 16), "100"));
-  assert(assert_string_equal(convert_number_from_base_to_another("FFFFFF", 16, 10), "16777215"));
-  assert(assert_string_equal(convert_number_from_base_to_another("1D57", 17, 35), "75C"));
-  assert(assert_string_equal(convert_number_from_base_to_another("80E", 20, 5), "100324"));
-  assert(assert_string_equal(convert_number_from_base_to_another("99", 10, 10), "99"));
-  assert(assert_string_equal(convert_number_from_base_to_another("3433024", 6, 28), "8008"));
-  assert(assert_string_equal(convert_number_from_base_to_another("30288G3A", 17, 36), "KF12OI"));
-  assert(assert_string_equal(convert_number_from_base_to_another("10", 9, 9), "10"));
-  assert(assert_string_equal(convert_number_from_base_to_another("10E", 23, 8), "1037"));
+  char* result = convert_number_from_base_to_another("15", 10, 16);
+  assert(assert_string_equal(result, "F"));
+  free(result);
+
+  result = convert_number_from_base_to_another("100000000", 2, 16);
+  assert(assert_string_equal(result, "100"));
+  free(result);
+
+  result = convert_number_from_base_to_another("FFFFFF", 16, 10);
+  assert(assert_string_equal(result, "16777215"));
+  free(result);
+
+  result = convert_number_from_base_to_another("1D57", 17, 35);
+  assert(assert_string_equal(result, "75C"));
+  free(result);
+
+  result = convert_number_from_base_to_another("80E", 20, 5);
+  assert(assert_string_equal(result, "100324"));
+  free(result);
+
+  result = convert_number_from_base_to_another("99", 10, 10);
+  assert(assert_string_equal(result, "99"));
+  free(result);
+
+  result = convert_number_from_base_to_another("3433024", 6, 28);
+  assert(assert_string_equal(result, "8008"));
+  free(result);
+
+  result = convert_number_from_base_to_another("30288G3A", 17, 36);
+  assert(assert_string_equal(result, "KF12OI"));
+  free(result);
+
+  result = convert_number_from_base_to_another("10", 9, 9);
+  assert(assert_string_equal(result, "10"));
+  free(result);
+
+  result = convert_number_from_base_to_another("10E", 23, 8);
+  assert(assert_string_equal(result, "1037"));
+  free(result);
 }

test/hash_map_test.c

@@ -24,4 +24,5 @@ void hash_map_test() {
   hash_map_remove(hash_map, "key5");
   assert(hash_map->length == 5);
   assert(!hash_map_contains_key(hash_map, "key5"));
+  hash_map_free(hash_map);
 }

test/linked_list_test.c

@@ -13,6 +13,7 @@ void linked_list_initialization_test() {
   struct linked_list *list = linked_list_initialization();
   assert(list->length == 0);
   assert(list->head == NULL);
+  linked_list_free(list);
 }
 
 void linked_list_add_in_head_test() {
@@ -25,6 +26,7 @@ void linked_list_add_in_head_test() {
   assert(((uintptr_t)list->head->next->data) == 8);
   assert(((uintptr_t)list->head->next->next->data) == 4);
   assert(list->head->next->next->next == NULL);
+  linked_list_free(list);
 }
 
 void linked_list_delete_in_head_test() {
@@ -37,6 +39,7 @@ void linked_list_delete_in_head_test() {
   assert(((uintptr_t)list->head->data) == 8);
   assert(((uintptr_t)list->head->next->data) == 4);
   assert(list->head->next->next == NULL);
+  linked_list_free(list);
 }
 
 void linked_list_add_after_last_test() {
@@ -54,6 +57,7 @@ void linked_list_add_after_last_test() {
   assert(((uintptr_t)list->head->next->data) == 8);
   assert(((uintptr_t)list->head->next->next->data) == 4);
   assert(((uintptr_t)list->head->next->next->next->data) == 18);
+  linked_list_free(list);
 }
 
 void linked_list_reverse_test() {
@@ -74,6 +78,8 @@ void linked_list_reverse_test() {
   assert((list_reversed->head->next->data) == (void *)'C');
   assert((list_reversed->head->next->next->data) == (void *)'B');
   assert((list_reversed->head->next->next->next->data) == (void *)'A');
+  linked_list_free(list);
+  linked_list_free(list_reversed);
 }
 
 void linked_list_reverse_mutate_test() {
@@ -89,4 +95,5 @@ void linked_list_reverse_mutate_test() {
   assert((list->head->next->data) == (void *)'C');
   assert((list->head->next->next->data) == (void *)'B');
   assert((list->head->next->next->next->data) == (void *)'A');
+  linked_list_free(list);
 }

test/queue_test.c

@@ -10,6 +10,7 @@ void queue_initialization_test() {
   struct queue *queue = queue_initialization();
   assert(queue->length == 0);
   assert(queue->first == NULL);
+  queue_free(queue);
 }
 
 void queue_push_test() {
@@ -22,6 +23,7 @@ void queue_push_test() {
   assert(((uintptr_t)queue->first->next->data) == 8);
   assert(((uintptr_t)queue->first->next->next->data) == 15);
   assert(queue->first->next->next->next == NULL);
+  queue_free(queue);
 }
 
 void queue_pop_test() {
@@ -35,4 +37,5 @@ void queue_pop_test() {
   assert(((uintptr_t)queue->first->data) == 8);
   assert(((uintptr_t)queue->first->next->data) == 15);
   assert(queue->first->next->next == NULL);
+  queue_free(queue);
 }

test/stack_test.c

@@ -10,6 +10,7 @@ void stack_initialization_test() {
   struct stack *stack = stack_initialization();
   assert(stack->length == 0);
   assert(stack->first == NULL);
+  stack_free(stack);
 }
 
 void stack_push_test() {
@@ -22,6 +23,7 @@ void stack_push_test() {
   assert(((uintptr_t)stack->first->next->data) == 8);
   assert(((uintptr_t)stack->first->next->next->data) == 4);
   assert(stack->first->next->next->next == NULL);
+  stack_free(stack);
 }
 
 void stack_pop_test() {
@@ -35,4 +37,5 @@ void stack_pop_test() {
   assert(((uintptr_t)stack->first->data) == 8);
   assert(((uintptr_t)stack->first->next->data) == 4);
   assert(stack->first->next->next == NULL);
+  stack_free(stack);
 }

test/string_test.c

@@ -30,42 +30,49 @@ 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 = string_to_uppercase(string);
+  string_t string = string_copy("heLlO world");
+  string_to_uppercase(string);
   assert(assert_string_equal(string, "HELLO WORLD"));
+  free(string);
 }
 
 void string_to_lowercase_test() {
-  string_t string = "HellO WoRLd";
-  string = string_to_lowercase(string);
+  string_t string = string_copy("HellO WoRLd");
+  string_to_lowercase(string);
   assert(assert_string_equal(string, "hello world"));
+  free(string);
 }
 
 void string_replace_test() {
-  string_t string = "hello world";
-  string = string_replace(string, 'l', 'z');
+  string_t string = string_copy("hello world");
+  string_replace(string, 'l', 'z');
   assert(assert_string_equal(string, "hezzo worzd"));
+  free(string);
 }
 
 void string_trim_start_test() {
-  string_t string = "      hello world      ";
-  string = string_trim_start(string);
+  string_t string = string_copy("      hello world      ");
+  string_trim_start(string, ' ');
   assert(assert_string_equal(string, "hello world      "));
+  free(string);
 }
 
 void string_trim_end_test() {
-  string_t string = "      hello world      ";
-  string = string_trim_end(string);
+  string_t string = string_copy("      hello world      ");
+  string_trim_end(string, ' ');
   assert(assert_string_equal(string, "      hello world"));
+  free(string);
 }
 
 void string_trim_test() {
-  string_t string = "      hello world      ";
-  string = string_trim(string);
+  string_t string = string_copy("      hello world      ");
+  string_trim(string, ' ');
   assert(assert_string_equal(string, "hello world"));
+  free(string);
 }
 
 void string_copy_test() {
@@ -76,12 +83,14 @@ void string_copy_test() {
   assert(assert_string_not_equal(string, string2));
   assert(assert_string_equal(string, "hello world"));
   assert(assert_string_equal(string2, "aello world"));
+  free(string2);
 }
 
 void string_capitalize_test() {
-  string_t string = "hello world";
-  string = string_capitalize(string);
+  string_t string = string_copy("hello world");
+  string_capitalize(string);
   assert(assert_string_equal(string, "Hello world"));
+  free(string);
 }
 
 void string_total_occurrences_of_character_test() {
@@ -90,9 +99,10 @@ void string_total_occurrences_of_character_test() {
 }
 
 void string_reverse_test() {
-  string_t string = "hello world";
-  string = string_reverse(string);
+  string_t string = string_copy("hello world");
+  string_reverse(string);
   assert(assert_string_equal(string, "dlrow olleh"));
+  free(string);
 }
 
 void string_equals_test() {
@@ -125,6 +135,10 @@ void string_split_test() {
   assert(assert_string_equal(result[1], "def"));
   assert(assert_string_equal(result[2], "ghij"));
   assert(assert_string_equal(result[3], "kl"));
+  for (size_t index = 0; index < result_length; index++) {
+    free(result[index]);
+  }
+  free(result);
 }
 
 void string_join_test() {
@@ -135,11 +149,24 @@ void string_join_test() {
   string_t new_string2 = string_join(result, '+', result_length);
   assert(assert_string_equal(new_string, string));
   assert(assert_string_equal(new_string2, "abc+def+ghij+kl"));
+  free(new_string);
+  free(new_string2);
+  for (size_t index = 0; index < result_length; index++) {
+    free(result[index]);
+  }
+  free(result);
 }
 
 void string_concatenate_test() {
-  assert(assert_string_equal(string_concatenate("abc", "def"), "abcdef"));
-  assert(assert_string_equal(string_concatenate("abc ", " defghi"), "abc  defghi"));
+  string_t result = string_copy("abc");
+  string_concatenate(&result, "def");
+  assert(assert_string_equal(result, "abcdef"));
+  free(result);
+
+  result = string_copy("abcz");
+  string_concatenate(&result, "  defghi");
+  assert(assert_string_equal(result, "abcz  defghi"));
+  free(result);
 }
 
 void string_get_has_unique_characters_test() {
@@ -152,6 +179,7 @@ void string_substring_test() {
   string_t string = "abcdef";
   string_t substring = string_substring(string, 1, 3);
   assert(assert_string_equal(substring, "bcd"));
+  free(substring);
 }
 
 void string_get_is_substring_test() {
@@ -167,33 +195,61 @@ void string_get_is_substring_test() {
 }
 
 void string_get_formatted_number_test() {
-  assert(assert_string_equal(string_get_formatted_number(1000, " "), "1 000"));
-  assert(assert_string_equal(string_get_formatted_number(123, ","), "123"));
-  assert(assert_string_equal(string_get_formatted_number(1234, ","), "1,234"));
-  assert(assert_string_equal(string_get_formatted_number(12345, ","), "12,345"));
-  assert(assert_string_equal(string_get_formatted_number(123456, ","), "123,456"));
-  assert(assert_string_equal(string_get_formatted_number(1234567, ","), "1,234,567"));
-  assert(assert_string_equal(string_get_formatted_number(12345678, ","), "12,345,678"));
-  assert(assert_string_equal(string_get_formatted_number(123456789, ","), "123,456,789"));
-  assert(assert_string_equal(string_get_formatted_number(1234567890, ","), "1,234,567,890"));
-  assert(assert_string_equal(string_get_formatted_number(-123, ","), "-123"));
-  assert(assert_string_equal(string_get_formatted_number(-1234, ","), "-1,234"));
-  assert(assert_string_equal(string_get_formatted_number(-12345, ","), "-12,345"));
-  assert(assert_string_equal(string_get_formatted_number(-123456, ","), "-123,456"));
-  assert(assert_string_equal(string_get_formatted_number(-1234567, ","), "-1,234,567"));
-  assert(assert_string_equal(string_get_formatted_number(-12345678, ","), "-12,345,678"));
-  assert(assert_string_equal(string_get_formatted_number(-123456789, ","), "-123,456,789"));
-  assert(assert_string_equal(string_get_formatted_number(-1234567890, ","), "-1,234,567,890"));
+  char* result = string_get_formatted_number(1000, " ");
+  assert(assert_string_equal(result, "1 000"));
+  free(result);
+
+  result = string_get_formatted_number(123, ",");
+  assert(assert_string_equal(result, "123"));
+  free(result);
+
+  result = string_get_formatted_number(1234, ",");
+  assert(assert_string_equal(result, "1,234"));
+  free(result);
+
+  result = string_get_formatted_number(12345, ",");
+  assert(assert_string_equal(result, "12,345"));
+  free(result);
+
+  result = string_get_formatted_number(-123, ",");
+  assert(assert_string_equal(result, "-123"));
+  free(result);
+
+  result = string_get_formatted_number(-1234, ",");
+  assert(assert_string_equal(result, "-1,234"));
+  free(result);
+
+  result = string_get_formatted_number(-1234567890, ",");
+  assert(assert_string_equal(result, "-1,234,567,890"));
+  free(result);
 }
 
 void string_get_last_occurence_of_character_test() {
   string_t string = "abcdef";
-  assert(assert_string_equal(string_get_last_occurence_of_character(string, 'a'), "abcdef"));
-  assert(assert_string_equal(string_get_last_occurence_of_character(string, 'b'), "bcdef"));
-  assert(assert_string_equal(string_get_last_occurence_of_character(string, 'c'), "cdef"));
-  assert(assert_string_equal(string_get_last_occurence_of_character(string, 'd'), "def"));
-  assert(assert_string_equal(string_get_last_occurence_of_character(string, 'e'), "ef"));
-  assert(assert_string_equal(string_get_last_occurence_of_character(string, 'f'), "f"));
+
+  char* result = string_get_last_occurence_of_character(string, 'a');
+  assert(assert_string_equal(result, "abcdef"));
+  free(result);
+
+  result = string_get_last_occurence_of_character(string, 'b');
+  assert(assert_string_equal(result, "bcdef"));
+  free(result);
+
+  result = string_get_last_occurence_of_character(string, 'c');
+  assert(assert_string_equal(result, "cdef"));
+  free(result);
+
+  result = string_get_last_occurence_of_character(string, 'd');
+  assert(assert_string_equal(result, "def"));
+  free(result);
+
+  result = string_get_last_occurence_of_character(string, 'e');
+  assert(assert_string_equal(result, "ef"));
+  free(result);
+
+  result = string_get_last_occurence_of_character(string, 'f');
+  assert(assert_string_equal(result, "f"));
+  free(result);
 }
 
 void string_starts_with_test() {

version.h

@@ -1,4 +1,4 @@
 #ifndef __LIBCPROJECT_VERSION__
-#define __LIBCPROJECT_VERSION__ "2.0.0"
+#define __LIBCPROJECT_VERSION__ "4.0.0"
 
 #endif