Short introduction to header files in C

main.c

string_utils.c

string_utils.h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "string_utils.h"

int main(int argc, char* argv[]) {
    char str[100] = "The apples are delicious apples";
    printf("%s\n", str);
    while(string_replace(str, 100, "apples", "hamburgers"));
    printf("%s\n", str);
    return 0;
}