Size_t s2len = strlen (s2);
size_t s2len = strlen (s2);
strindex (s1, s2)/*   returns a pointer to the first occurrence of s2 in s1, or NULL if there are   none. */register char *s1, *s2;{	register char *s3;	Size_t s2len = strlen (s2);	while ((s3 = strchr(s1, *s2)) != NULL)	{		if (strncmp (s3, s2, s2len) == 0) return (s3);		s1 = ++s3;	}	return (NULL);}