mirror of https://github.com/mkerrisk/man-pages
115 lines
2.8 KiB
Groff
115 lines
2.8 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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.\" Dinkumware C library reference http://www.dinkumware.com/
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.\" OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
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.\" ISO/IEC 9899:1999
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.\"
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.TH MBLEN 3 2015-08-08 "GNU" "Linux Programmer's Manual"
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.SH NAME
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mblen \- determine number of bytes in next multibyte character
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.PP
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.BI "int mblen(const char *" s ", size_t " n );
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.fi
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.SH DESCRIPTION
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If
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.I s
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is not NULL, the
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.BR mblen ()
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function inspects at most
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.I n
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bytes of the multibyte string starting at
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.I s
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and extracts the
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next complete multibyte character.
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It uses a static anonymous shift state known only to the
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.BR mblen ()
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function.
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If the multibyte character is not the null wide
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character, it returns the number of bytes that were consumed from
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.IR s .
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If the multibyte character is the null wide character, it returns 0.
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.PP
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If the
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.IR n
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bytes starting at
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.I s
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do not contain a complete multibyte
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character,
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.BR mblen ()
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returns \-1.
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This can happen even if
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.I n
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is greater than or equal to
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.IR MB_CUR_MAX ,
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if the multibyte string contains redundant shift sequences.
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.PP
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If the multibyte string starting at
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.I s
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contains an invalid multibyte
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sequence before the next complete character,
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.BR mblen ()
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also returns \-1.
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.PP
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If
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.I s
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is NULL, the
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.BR mblen ()
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function
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.\" The Dinkumware doc and the Single UNIX specification say this, but
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.\" glibc doesn't implement this.
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resets the shift state, known to only this function, to the initial state, and
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returns nonzero if the encoding has nontrivial shift state, or zero if the
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encoding is stateless.
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.SH RETURN VALUE
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The
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.BR mblen ()
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function returns the number of
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bytes parsed from the multibyte
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sequence starting at
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.IR s ,
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if a non-null wide character was recognized.
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It returns 0, if a null wide character was recognized.
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It returns \-1, if an
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invalid multibyte sequence was encountered or if it couldn't parse a complete
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multibyte character.
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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 mblen ()
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T} Thread safety MT-Unsafe race
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.TE
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008, C99.
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.SH NOTES
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The behavior of
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.BR mblen ()
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depends on the
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.B LC_CTYPE
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category of the
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current locale.
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.PP
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The function
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.BR mbrlen (3)
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provides a better interface to the same
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functionality.
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.SH SEE ALSO
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.BR mbrlen (3)
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