string concatenator

void mystrcat(char *s, char *t)
{
    printf("%s, %s\n", s, t);
    int len = 0;
    while (*s++ != '\0')
        len++;

    s += len;

    int i = 0;
    while (i++ < len)
        *(s + i) = *t++;
    *(s + i) = '\0';
}