mirror of https://github.com/mkerrisk/man-pages
87 lines
1.7 KiB
Groff
87 lines
1.7 KiB
Groff
.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
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.\"
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.\" %%%LICENSE_START(GPLv2+_DOC_ONEPARA)
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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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.\" %%%LICENSE_END
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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 2020-12-21 "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 #include <string.h>
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.PP
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.BI "size_t strnlen(const char *" s ", size_t " maxlen );
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.fi
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.PP
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.RS -4
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.RE
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.PP
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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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_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 bytes in the string
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pointed to by
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.IR s ,
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excluding the terminating null byte (\(aq\e0\(aq),
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but at most
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.IR maxlen .
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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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.I maxlen
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characters in the string pointed to by
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.I s
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and never beyond
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.IR s[maxlen\-1] .
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.SH RETURN VALUE
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The
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.BR strnlen ()
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function returns
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.IR strlen(s) ,
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if that is less than
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.IR maxlen ,
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or
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.I maxlen
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if there is no null terminating (\(aq\e0\(aq) among the first
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.I maxlen
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characters pointed to by
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.IR s .
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR strnlen ()
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T} Thread safety MT-Safe
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.TE
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.SH CONFORMING TO
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POSIX.1-2008.
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.SH SEE ALSO
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.BR strlen (3)
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