char *strcat(char *destination, const char *source) {
        int i = 0, j = 0;
        while (destination[i] != char(0) && source[j] != char(0)) {
            if (destination[i] != char(0)) {
                i++;
            }
            if (source[j] != char(0)) {
                j++;
            }
        }
        int t = i + j - 1;
        j = 0;
        while (i != t) {
            destination[i] = source[j];
            i++;
            j++;
        }
        destination[t] = char(0);
        return destination;
    }
}