linux man page for memchr

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

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 (inter-
       preted as an unsigned character) stops the operation.

       The memrchr() function is like the memchr() function, except that it searches backwards from the end of the n bytes pointed to by s instead
       of forwards 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  argu-
       ment,  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 folowing call is a fast means of locating a string's terminating null byte:

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

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 3.27 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/.

								    2009-12-04								 MEMCHR(3)