Thread: Confused about pointer solution for K&R stringcat problem

Hi all.
I was trying Exercise 5-3 from the K&R book where you rewrite this function version using pointers:

Code:

void stringcat(char s[], const char t[]) {
    int i, j;
    i = j = 0;
    while (s[i] != '\0')
        i++;
    while ((s[i++] = t[j++]) != '\0')
        ;
}

My solution (wrong) was to try something like this:

Code:

void stringcatp(char s[], const char t[]) {
    while (*s++ != '\0')
        ;
    while ((*s++ = *t++))
        ;
}

I finally gave up and looked at the solution:

Code:

void stringcatp(char s[], const char t[]) {
    while (*s) /* find end of s */
        s++;
    while ((*s++ = *t++)) /* copy t */
        ;
}

However I am confused... what is the difference between while (*s) with s++ in the while body compared to my way?