240 lines
5.0 KiB
HTML
240 lines
5.0 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of MEMCHR</TITLE>
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</HEAD><BODY>
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<H1>MEMCHR</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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memchr, memrchr, rawmemchr - scan memory for a character
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/string.h">string.h</A>></B>
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<B>void *memchr(const void *</B><I>s</I><B>, int </B><I>c</I><B>, size_t </B><I>n</I><B>);</B>
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<B>void *memrchr(const void *</B><I>s</I><B>, int </B><I>c</I><B>, size_t </B><I>n</I><B>);</B>
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<B>void *rawmemchr(const void *</B><I>s</I><B>, int </B><I>c</I><B>);</B>
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</PRE>
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>memrchr</B>(),
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<B>rawmemchr</B>():
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_GNU_SOURCE
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>memchr</B>()
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function scans the initial
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<I>n</I>
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bytes of the memory
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area pointed to by
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<I>s</I>
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for the first instance of
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<I>c</I>.
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Both
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<I>c</I>
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and the bytes of the memory area pointed to by
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<I>s</I>
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are interpreted as
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<I>unsigned char</I>.
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<P>
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The
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<B>memrchr</B>()
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function is like the
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<B>memchr</B>()
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function,
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except that it searches backward from the end of the
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<I>n</I>
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bytes pointed to by
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<I>s</I>
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instead of forward from the beginning.
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<P>
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The
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<B>rawmemchr</B>()
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function is similar to
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<B>memchr</B>():
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it assumes (i.e., the programmer knows for certain)
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that an instance of
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<I>c</I>
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lies somewhere in the memory area starting at the location pointed to by
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<I>s</I>,
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and so performs an optimized search for
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<I>c</I>
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(i.e., no use of a count argument to limit the range of the search).
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If an instance of
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<I>c</I>
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is not found, the results are unpredictable.
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The following call is a fast means of locating a string's
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terminating null byte:
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<P>
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char *p = rawmemchr(s, '\0');
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The
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<B>memchr</B>()
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and
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<B>memrchr</B>()
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functions return a pointer
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to the matching byte or NULL if the character does not occur in
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the given memory area.
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<P>
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The
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<B>rawmemchr</B>()
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function returns a pointer to the matching byte, if one is found.
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If no matching byte is found, the result is unspecified.
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<A NAME="lbAF"> </A>
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<H2>VERSIONS</H2>
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<B>rawmemchr</B>()
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first appeared in glibc in version 2.1.
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<P>
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<B>memrchr</B>()
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first appeared in glibc in version 2.2.
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>memchr</B>(),
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<B>memrchr</B>(),
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<B>rawmemchr</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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<B>memchr</B>():
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POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
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<P>
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The
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<B>memrchr</B>()
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function is a GNU extension, available since glibc 2.1.91.
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<P>
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The
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<B>rawmemchr</B>()
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function is a GNU extension, available since glibc 2.1.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+bstring">bstring</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+ffs">ffs</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+index">index</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+memmem">memmem</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+rindex">rindex</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+strchr">strchr</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+strpbrk">strpbrk</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+strrchr">strrchr</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+strsep">strsep</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+strspn">strspn</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+strstr">strstr</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+wmemchr">wmemchr</A></B>(3)
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<A NAME="lbAJ"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="5"><A HREF="#lbAF">VERSIONS</A><DD>
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<DT id="6"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="7"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="8"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="9"><A HREF="#lbAJ">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:48 GMT, March 31, 2021
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