mirror of https://github.com/mkerrisk/man-pages
110 lines
2.6 KiB
Groff
110 lines
2.6 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 MBSTOWCS 3 2011-09-28 "GNU" "Linux Programmer's Manual"
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.SH NAME
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mbstowcs \- convert a multibyte string to a wide-character string
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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 "size_t mbstowcs(wchar_t *" dest ", const char *" src ", size_t " n );
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.fi
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.SH DESCRIPTION
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If
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.I dest
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is not a NULL pointer,
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the
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.BR mbstowcs ()
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function converts the
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multibyte string
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.I src
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to a wide-character string starting at
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.IR dest .
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At most
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.I n
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wide characters are written to
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.IR dest .
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The conversion starts
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in the initial state.
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The conversion can stop for three reasons:
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.IP 1. 3
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An invalid multibyte sequence has been encountered.
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In this case
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.I (size_t)\ \-1
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is returned.
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.IP 2.
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.I n
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non-L\(aq\\0\(aq wide characters have been stored at
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.IR dest .
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In this
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case the number of wide characters written to
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.I dest
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is returned, but the
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shift state at this point is lost.
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.IP 3.
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The multibyte string has been completely converted, including the
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terminating null wide character (\(aq\\0\(aq).
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In this case the number of wide characters written to
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.IR dest ,
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excluding the terminating null wide character, is returned.
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.PP
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The programmer must ensure that there is room for at least
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.I n
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wide
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characters at
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.IR dest .
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.PP
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If
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.IR dest
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is NULL,
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.I n
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is ignored, and the conversion proceeds as
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above, except that the converted wide characters are not written out to memory,
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and that no length limit exists.
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.PP
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In order to avoid the case 2 above, the programmer should make sure
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.I n
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is
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greater or equal to
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.IR "mbstowcs(NULL,src,0)+1" .
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.SH RETURN VALUE
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The
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.BR mbstowcs ()
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function returns the number of wide characters that make
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up the converted part of the wide-character string, not including the
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terminating null wide character.
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If an invalid multibyte sequence was
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encountered,
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.I (size_t)\ \-1
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is returned.
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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 mbstowcs ()
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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 mbsrtowcs (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 mbsrtowcs (3),
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.BR wcstombs (3)
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