mirror of https://github.com/mkerrisk/man-pages
63 lines
1.5 KiB
Groff
63 lines
1.5 KiB
Groff
.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" References consulted:
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.\" GNU glibc-2 source code and manual
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.\"
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.TH STRNLEN 3 2010-09-15 "GNU" "Linux Programmer's Manual"
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.SH NAME
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strnlen \- determine the length of a fixed-size string
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.SH SYNOPSIS
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.nf
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.B #define _GNU_SOURCE
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.sp
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.B #include <string.h>
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.sp
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.BI "size_t strnlen(const char *" s ", size_t " maxlen );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR strnlen ():
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.PD 0
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.ad l
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.RS 4
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.TP 4
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Since glibc 2.10:
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_XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L
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.TP
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Before glibc 2.10:
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_GNU_SOURCE
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.RE
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.ad
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.PD
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.SH DESCRIPTION
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The
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.BR strnlen ()
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function returns the number of characters in the string
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pointed to by \fIs\fP, not including the terminating \(aq\\0\(aq character,
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but at most \fImaxlen\fP.
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In doing this,
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.BR strnlen ()
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looks only at the first
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\fImaxlen\fP characters at \fIs\fP and never beyond \fIs+maxlen\fP.
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.SH "RETURN VALUE"
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The
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.BR strnlen ()
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function returns \fIstrlen(s)\fP, if that is less than
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\fImaxlen\fP, or \fImaxlen\fP
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if there is no \(aq\\0\(aq character among the first
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\fImaxlen\fP characters pointed to by \fIs\fP.
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.SH "CONFORMING TO"
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This function is a GNU extension.
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.SH "SEE ALSO"
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.BR strlen (3),
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.BR feature_test_macros (7)
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