Character string search (start position)
char *strpbrk(const char *s1, const char *s2);
Returns the pointer indicating this character. If any of the characters from s2 does not appear in s1, the null pointer is returned.
This function obtains the position in the character string indicated by s1 at which any of the characters in the character string indicated by s2 (except the null character (\0)) appears first.