test.c

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

int main(){
    char first[] = "Hello!";
    char * second;
    cpy(&second, first);
    printf("second: %s\n", second);
    char * third;
    cat(&second, " World!");
    cpy(&third, second);
    printf("third: %s\n", third);

    return 0;
}