1MEMMEM(3)                  Linux Programmer's Manual                 MEMMEM(3)
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NAME

6       memmem - locate a substring
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SYNOPSIS

9       #define _GNU_SOURCE
10       #include <string.h>
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12       void *memmem(const void *haystack, size_t haystacklen,
13                    const void *needle, size_t needlelen);
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DESCRIPTION

16       The  memmem()  function  finds the start of the first occurrence of the
17       substring needle of length needlelen in the  memory  area  haystack  of
18       length haystacklen.
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RETURN VALUE

21       The  memmem()  function  returns a pointer to the beginning of the sub‐
22       string, or NULL if the substring is not found.
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CONFORMING TO

25       This function is a GNU extension.
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BUGS

28       This function was broken in Linux libraries up to  and  including  libc
29       5.0.9;  there  the `needle' and `haystack' arguments were interchanged,
30       and a pointer to  the  end  of  the  first  occurrence  of  needle  was
31       returned.   Since  libc 5.0.9 is still widely used, this is a dangerous
32       function to use.
33       Both old and new libc's have the bug that if needle is empty haystack-1
34       (instead  of  haystack) is returned.  And glibc 2.0 makes it worse, and
35       returns a pointer to the last byte of  `haystack'.  This  is  fixed  in
36       glibc 2.1.
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SEE ALSO

39       strstr(3), feature_test_macros(7)
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43GNU                               1998-01-13                         MEMMEM(3)