MEMMEM

Section: Linux Programmer's Manual (3)
Updated: 2008-12-05
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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.

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, returning a pointer to the last byte of haystack. This is fixed in glibc 2.1.

COLOPHON

This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.