man3/mbstowcs.3

   1 .\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
   2 .\"
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   8 .\" References consulted:
   9 .\"   GNU glibc-2 source code and manual
  10 .\"   Dinkumware C library reference http://www.dinkumware.com/
  11 .\"   OpenGroup's Single Unix specification http://www.UNIX-systems.org/online.html
  12 .\"   ISO/IEC 9899:1999
  13 .\"
  14 .TH MBSTOWCS 3  1999-07-25 "GNU" "Linux Programmer's Manual"
  15 .SH NAME
  16 mbstowcs \- convert a multibyte string to a wide character string
  17 .SH SYNOPSIS
  18 .nf
  19 .B #include <stdlib.h>
  20 .sp
  21 .BI "size_t mbstowcs(wchar_t *" dest ", const char *" src ", size_t " n );
  22 .fi
  23 .SH DESCRIPTION
  24 If \fIdest\fP is not a NULL pointer, the \fBmbstowcs\fP function converts the
  25 multibyte string \fIsrc\fP to a wide-character string starting at \fIdest\fP.
  26 At most \fIn\fP wide characters are written to \fIdest\fP. The conversion starts
  27 in the initial state. The conversion can stop for three reasons:
  28 .PP
  29 1. An invalid multibyte sequence has been encountered. In this case
  30 (size_t)(\-1) is returned.
  31 .PP
  32 2. \fIn\fP non-L'\\0' wide characters have been stored at \fIdest\fP. In this
  33 case the number of wide characters written to \fIdest\fP is returned, but the
  34 shift state at this point is lost.
  35 .PP
  36 3. The multibyte string has been completely converted, including the
  37 terminating '\\0'. In this case the number of wide characters written to
  38 \fIdest\fP, excluding the terminating L'\\0' character, is returned.
  39 .PP
  40 The programmer must ensure that there is room for at least \fIn\fP wide
  41 characters at \fIdest\fP.
  42 .PP
  43 If \fIdest\fP is NULL, \fIn\fP is ignored, and the conversion proceeds as
  44 above, except that the converted wide characters are not written out to memory,
  45 and that no length limit exists.
  46 .PP
  47 In order to avoid the case 2 above, the programmer should make sure \fIn\fP is
  48 greater or equal to \fImbstowcs(NULL,src,0)+1\fP.
  49 .SH "RETURN VALUE"
  50 The \fBmbstowcs\fP function returns the number of wide characters that make
  51 up the converted part of the wide character string, not including the
  52 terminating null wide character. If an invalid multibyte sequence was
  53 encountered, (size_t)(\-1) is returned.
  54 .SH "CONFORMING TO"
  55 ISO/ANSI C, UNIX98
  56 .SH "SEE ALSO"
  57 .BR mbsrtowcs (3)
  58 .SH NOTES
  59 The behaviour of \fBmbstowcs\fP depends on the LC_CTYPE category of the
  60 current locale.
  61 .PP
  62 The function \fBmbsrtowcs\fP provides a better interface to the same
  63 functionality.