programming-challenges/challenges/is-palindrome/solutions/c/function/string.c

#include "string.h"

#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

#include "character.h"

char* string_to_upper(const char* string) {
  size_t string_length = strlen(string);
  char* result = malloc(sizeof(char) * (string_length + 1));
  for (size_t index = 0; index < string_length; index++) {
    character_append(result, character_to_upper(string[index]));
  }
  return result;
}

char* string_reverse(const char* string) {
  size_t string_length = strlen(string);
  char* result = malloc(sizeof(char) * (string_length + 1));
  for (size_t index = string_length - 1; index != -1; index--) {
    character_append(result, string[index]);
  }
  return result;
}

bool string_is_palindrome(const char* string) {
  char* string_reversed = string_reverse(string);
  bool is_palindrome = strcmp(string_reversed, string) == 0;
  free(string_reversed);
  return is_palindrome;
}

char* string_replace(const char* string, char search_value,
                     char replace_value) {
  size_t string_length = strlen(string);
  char* result = malloc(sizeof(char) * (string_length + 1));
  for (size_t index = 0; index < string_length; index++) {
    bool is_search_value = search_value == string[index];
    if (is_search_value) {
      character_append(result, replace_value);
    } else {
      character_append(result, string[index]);
    }
  }
  return result;
}