redhat man page for memmem

MEMMEM(3)						     Linux Programmer's Manual							 MEMMEM(3)

NAME
       memmem - locate a substring

SYNOPSIS
       #define _GNU_SOURCE
       #include <string.h>

       void *memmem(const void *haystack, size_t haystacklen,
		    const void *needle, size_t needlelen);

DESCRIPTION
       The  memmem()  function	finds the start of the first occurrence of the substring needle of length needlelen in the memory area haystack of
       length haystacklen.

RETURN VALUE
       The memmem() function returns a pointer to the beginning of the substring, or NULL if the substring is not found.

CONFORMING TO
       This function is a GNU extension.

BUGS
       This function was broken in Linux libraries up to and including libc 5.0.9; there the `needle' and `haystack' arguments were  interchanged,
       and  a pointer to the end of the first occurrence of needle was returned.  Since libc 5.0.9 is still widely used, this is a dangerous func-
       tion to use.
       Both old and new libc's have the bug that if needle is empty haystack-1 (instead of haystack) is returned.  And glibc 2.0 makes	it  worse,
       and returns a pointer to the last byte of `haystack'. This is fixed in glibc 2.1.

SEE ALSO
       strstr(3)

GNU
								    1998-01-13								 MEMMEM(3)