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); |
![[Note]](../stylesheet/note.png) |
Note | ||
|---|---|---|---|
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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 3.33 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/.
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Copyright 1993 David Metcalfe (davidprism.demon.co.uk) and Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk <mtk.manpagesgmail.com> Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. Modified Mon Apr 12 12:49:57 1993, David Metcalfe Modified Sat Jul 24 18:56:22 1993, Rik Faith (faithcs.unc.edu) Modified Wed Feb 20 21:09:36 2002, Ian Redfern (redfernilogica.com) 2008-07-09, mtk, add rawmemchr() |