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NAME

       memchr, memrchr, rawmemchr - scan memory for a character

SYNOPSIS

       #include <string.h>

       void *memchr(const void *s, int c, size_t n);

       void *memrchr(const void *s, int c, size_t n);

       void *rawmemchr(const void *s, int c);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       memrchr(), rawmemchr(): _GNU_SOURCE

DESCRIPTION

       The  memchr()  function scans the first n bytes of the memory area pointed to by s for the
       character c.  The first byte to match c (interpreted as an unsigned character)  stops  the
       operation.

       The  memrchr()  function  is  like the memchr() function, except that it searches backward
       from the end of the n bytes pointed to by s instead of forward from the beginning.

       The rawmemchr() function is similar to memchr(): it assumes (i.e.,  the  programmer  knows
       for  certain)  that  the  character  c  lies somewhere in the string s, and so performs an
       optimized search for the character c (i.e., no checking for the terminating null byte,  or
       use  of  an  argument, n, to limit the range of the search).  If the character c is not in
       the string s, then rawmemchr() may proceed to search beyond the end of the string, and the
       result  is  unspecified.   The  following  call  is  a  fast  means of locating a string's
       terminating null byte:

           char *p = rawmemchr(s, '\0');

RETURN VALUE

       The memchr() and memrchr() functions return a pointer to the matching byte or NULL if  the
       character does not occur in the given memory area.

       The  rawmemchr()  function returns a pointer to the matching byte, if one is found.  If no
       matching byte is found, the result is unspecified.

VERSIONS

       rawmemchr() first appeared in glibc in version 2.1.

       memrchr() first appeared in glibc in version 2.2.

CONFORMING TO

       The memchr() function conforms to SVr4, 4.3BSD, C89, C99, POSIX.1-2001.

       The memrchr() function is a GNU extension, available since glibc 2.1.91.

       The rawmemchr() function is a GNU extension, available since glibc 2.1.

SEE ALSO

       ffs(3), index(3), rindex(3),  strchr(3),  strpbrk(3),  strrchr(3),  strsep(3),  strspn(3),
       strstr(3), wmemchr(3)

COLOPHON

       This  page  is  part of release 3.35 of the Linux man-pages project.  A description of the
       project, and information about reporting bugs, can be found at  http://man7.org/linux/man-
       pages/.

                                            2009-12-04                                  MEMCHR(3)