mirror of https://github.com/mkerrisk/man-pages
82 lines
2.5 KiB
Groff
82 lines
2.5 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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.\" 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 1999-07-25 "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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.sp
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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 \fIs\fP is not a NULL pointer, the
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.BR mblen ()
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function inspects at most
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\fIn\fP bytes of the multibyte string starting at \fIs\fP and extracts the
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next complete multibyte character.
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It uses a static anonymous shift state only
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known to the mblen 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 \fIs\fP.
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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 \fIn\fP bytes starting at \fIs\fP 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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\fIn\fP >= \fIMB_CUR_MAX\fP, if the multibyte string contains redundant shift
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sequences.
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.PP
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If the multibyte string starting at \fIs\fP 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 \fIs\fP is a NULL pointer, 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, only known to this function, to the initial state, and
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returns non-zero if the encoding has non-trivial 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 \fIs\fP, 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 "CONFORMING TO"
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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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