char* my_strcat(char* dest, char* src)
{
    char* res = dest;
    while (*dest) dest ++;
    while (*dest ++ = *src ++);
    return res;
}

int main()
{
    char firstName[30] = "Jim";
    char middleName[30] = "---";
    char lastName[30] = "Green";

    my_strcat(my_strcat(firstName, middleName), lastName);
    printf("%s\n", firstName);

//    char* p = firstName;
//    char* q = lastName;

//    while (*p) p ++;
//    while (1)
//    {
//        *p = *q;
//        if (*p == '\0') break;
//        p ++;
//        q ++;
//    }
//    printf("%s\n", firstName);

//    while (*p ++ = *q ++);
//    printf("%s\n", firstName);

    return 0;
}