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 (interpreted 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 termi-
       nating  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 folowing 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 3.25 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)