fix(solutions): memory issues thanks to -fsanitize=address flag with gcc

challenges/caesar-cipher/solutions/c/function/character.c

@@ -1,10 +1,15 @@
 #include "character.h"
 
-#include <stdlib.h>
-#include <string.h>
+void character_append(char* string, const char character) {
+  size_t length = string_get_length(string);
+  character_append_at(string, character, length);
+}
 
-void character_append(char* string, char character) {
-  size_t length = strlen(string);
-  string[length] = character;
+void character_append_at(char* 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[index_string] = string[index_string - 1];
+  }
+  string[index] = character;
   string[length + 1] = '\0';
 }

challenges/caesar-cipher/solutions/c/function/character.h

@@ -1,6 +1,11 @@
 #ifndef __CHARACTER__
 #define __CHARACTER__
 
+#include <stdlib.h>
+#include <string.h>
+
+#include "string.h"
+
 /**
  * @brief Append a character to a string, assuming string points to an array
  * with enough space.
@@ -10,4 +15,13 @@
  */
 void character_append(char* 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
+ * @param character
+ * @param index
+ */
+void character_append_at(char* string, const char character, const size_t index);
+
 #endif

challenges/caesar-cipher/solutions/c/function/input.c

@@ -1,8 +1,5 @@
 #include "input.h"
 
-#include <stdio.h>
-#include <stdlib.h>
-
 #include "character.h"
 
 char* input() {

challenges/caesar-cipher/solutions/c/function/input.h

@@ -1,6 +1,9 @@
 #ifndef __INPUT__
 #define __INPUT__
 
+#include <stdio.h>
+#include <stdlib.h>
+
 /**
  * @brief Read a line from stdin.
  *

challenges/caesar-cipher/solutions/c/function/solution.c

@@ -9,8 +9,9 @@ int main() {
   char* string = input();
   int shift;
   scanf("%d", &shift);
-  string = string_caesar_cipher(string, shift);
-  printf("%s\n", string);
+  char* result = string_caesar_cipher(string, shift);
+  printf("%s\n", result);
   free(string);
+  free(result);
   return EXIT_SUCCESS;
 }

challenges/caesar-cipher/solutions/c/function/string.c

@@ -1,24 +1,27 @@
 #include "string.h"
 
-#include <stdbool.h>
-#include <stdlib.h>
-#include <string.h>
-
 #include "character.h"
 
-#define ALPHABET_LENGTH 26
+size_t string_get_length(const char* string) {
+  size_t length = 0;
+  while (string[length] != '\0') {
+    length++;
+  }
+  return length;
+}
 
 char* string_shift_alphabet(int shift) {
   char* result = malloc(sizeof(char) * (ALPHABET_LENGTH + 1));
-  for (char index = 0; index < ALPHABET_LENGTH; index++) {
+  for (size_t index = 0; index < ALPHABET_LENGTH; index++) {
     char letter = 'A' + index + shift;
     if (letter < 'A') {
       letter = 'Z' + shift + index + 1;
     } else if (letter > 'Z') {
       letter = letter - ALPHABET_LENGTH;
     }
-    character_append(result, letter);
+    result[index] = letter;
   }
+  result[ALPHABET_LENGTH] = '\0';
   return result;
 }
 
@@ -28,8 +31,8 @@ char* string_caesar_cipher(char* string, int shift) {
   char* shifted_alphabet = string_shift_alphabet(shift);
   for (size_t index = 0; index < string_length; index++) {
     char letter = string[index];
-    if (letter != ' ') {
-      for (int index_alphabet = 0; index_alphabet < ALPHABET_LENGTH; index_alphabet++) {
+    if (letter != ' ' && (letter >= 'A' && letter <= 'Z')) {
+      for (size_t index_alphabet = 0; index_alphabet < ALPHABET_LENGTH; index_alphabet++) {
         char current_letter = 'A' + index_alphabet;
         if (string[index] == current_letter) {
           letter = shifted_alphabet[index_alphabet];
@@ -37,7 +40,9 @@ char* string_caesar_cipher(char* string, int shift) {
         }
       }
     }
-    character_append(result, letter);
+    result[index] = letter;
   }
+  result[string_length] = '\0';
+  free(shifted_alphabet);
   return result;
 }

challenges/caesar-cipher/solutions/c/function/string.h

@@ -1,8 +1,20 @@
 #ifndef __STRING__
 #define __STRING__
 
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ALPHABET_LENGTH 26
 #define ALPHABET "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 
+/**
+ * @brief Return the length of a string (excluding '\0').
+ *
+ * @param string
+ */
+size_t string_get_length(const char* string);
+
 /**
  * @brief Shift the alphabet by a given amount.
  *