memmem

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



NAME
       memmem - locate a substring

SYNOPSIS
       #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 function 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 (2.0.5) makes it worse, and
       returns a pointer to the last byte of `haystack'.  Hopefully this will be
       fixed. For the time being, memmem() should not be used with an empty
       `needle'.

SEE ALSO
       strstr(3)



GNU                             January 13, 1998                       MEMMEM(3)