NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | VERSIONS | CONFORMING TO | SEE ALSO | COLOPHON
MEMCHR(3) Linux Programmer's Manual MEMCHR(3)
memchr, memrchr, rawmemchr - scan memory for a character
#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)):
rawmemchr(): _GNU_SOURCE
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 terminating null byte, or use of an argument, n, to limit the
range of the search). If the chararacter c is not in the string s, then
rawmemchr() may proceeed 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');
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.
rawmemchr() first appeared in glibc in version 2.1.
memrchr() first appeared in glibc in version 2.2.
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.
index(3), rindex(3), strchr(3), strpbrk(3), strrchr(3), strsep(3), strspn(3),
strstr(3), wmemchr(3)
This page is part of release 3.11 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/.
2008-08-11 MEMCHR(3)