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 occur­
       rence 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  makes  it  worse, and returns a pointer to the
       last byte of `haystack'. This is fixed in glibc 2.1.


SEE ALSO

       strstr(3)


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