man3/mbstowcs.3

   1 .\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
   2 .\"
   3 .\" %%%LICENSE_START(GPLv2+_ONEPARA_DOC)
   4 .\" This is free documentation; you can redistribute it and/or
   5 .\" modify it under the terms of the GNU General Public License as
   6 .\" published by the Free Software Foundation; either version 2 of
   7 .\" the License, or (at your option) any later version.
   8 .\" %%%LICENSE_END
   9 .\"
  10 .\" References consulted:
  11 .\"   GNU glibc-2 source code and manual
  12 .\"   Dinkumware C library reference http://www.dinkumware.com/
  13 .\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
  14 .\"   ISO/IEC 9899:1999
  15 .\"
  16 .TH MBSTOWCS 3  2011-09-28 "GNU" "Linux Programmer's Manual"
  17 .SH NAME
  18 mbstowcs \- convert a multibyte string to a wide-character string
  19 .SH SYNOPSIS
  20 .nf
  21 .B #include <stdlib.h>
  22 .sp
  23 .BI "size_t mbstowcs(wchar_t *" dest ", const char *" src ", size_t " n );
  24 .fi
  25 .SH DESCRIPTION
  26 If \fIdest\fP is not a NULL pointer,
  27 the
  28 .BR mbstowcs ()
  29 function converts the
  30 multibyte string \fIsrc\fP to a wide-character string starting at \fIdest\fP.
  31 At most \fIn\fP wide characters are written to \fIdest\fP.
  32 The conversion starts
  33 in the initial state.
  34 The conversion can stop for three reasons:
  35 .IP 1. 3
  36 An invalid multibyte sequence has been encountered.
  37 In this case
  38 .I (size_t)\ \-1
  39 is returned.
  40 .IP 2.
  41 \fIn\fP non-L\(aq\\0\(aq wide characters have been stored at \fIdest\fP.
  42 In this
  43 case the number of wide characters written to \fIdest\fP is returned, but the
  44 shift state at this point is lost.
  45 .IP 3.
  46 The multibyte string has been completely converted, including the
  47 terminating null wide character (\(aq\\0\(aq).
  48 In this case the number of wide characters written to
  49 \fIdest\fP, excluding the terminating null wide character, is returned.
  50 .PP
  51 The programmer must ensure that there is room for at least \fIn\fP wide
  52 characters at \fIdest\fP.
  53 .PP
  54 If \fIdest\fP is NULL, \fIn\fP is ignored, and the conversion proceeds as
  55 above, except that the converted wide characters are not written out to memory,
  56 and that no length limit exists.
  57 .PP
  58 In order to avoid the case 2 above, the programmer should make sure \fIn\fP is
  59 greater or equal to \fImbstowcs(NULL,src,0)+1\fP.
  60 .SH RETURN VALUE
  61 The
  62 .BR mbstowcs ()
  63 function returns the number of wide characters that make
  64 up the converted part of the wide-character string, not including the
  65 terminating null wide character.
  66 If an invalid multibyte sequence was
  67 encountered,
  68 .I (size_t)\ \-1
  69 is returned.
  70 .SH CONFORMING TO
  71 C99.
  72 .SH NOTES
  73 The behavior of
  74 .BR mbstowcs ()
  75 depends on the
  76 .B LC_CTYPE
  77 category of the
  78 current locale.
  79 .PP
  80 The function
  81 .BR mbsrtowcs (3)
  82 provides a better interface to the same
  83 functionality.
  84 .SH SEE ALSO
  85 .BR mbsrtowcs (3),
  86 .BR wcstombs (3)