man3/mbsnrtowcs.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 .\"
  13 .TH MBSNRTOWCS 3  2007-07-26 "GNU" "Linux Programmer's Manual"
  14 .SH NAME
  15 mbsnrtowcs \- convert a multibyte string to a wide-character string
  16 .SH SYNOPSIS
  17 .nf
  18 .B #define _GNU_SOURCE
  19 .B #include <wchar.h>
  20 .sp
  21 .BI "size_t mbsnrtowcs(wchar_t *" dest ", const char **" src ,
  22 .BI "                  size_t " nms ", size_t " len ", mbstate_t *" ps );
  23 .fi
  24 .SH DESCRIPTION
  25 The
  26 .BR mbsnrtowcs ()
  27 function is like the
  28 .BR mbsrtowcs (3)
  29 function, except that
  30 the number of bytes to be converted, starting at \fI*src\fP, is limited to
  31 \fInms\fP.
  32 .PP
  33 If \fIdest\fP is not a NULL pointer, the
  34 .BR mbsnrtowcs ()
  35 function converts at
  36 most \fInms\fP bytes from the
  37 multibyte string \fI*src\fP to a wide-character string starting at \fIdest\fP.
  38 At most \fIlen\fP wide characters are written to \fIdest\fP.
  39 The shift state
  40 \fI*ps\fP is updated.
  41 The conversion is effectively performed by repeatedly
  42 calling
  43 .I "mbrtowc(dest, *src, n, ps)"
  44 where \fIn\fP is some
  45 positive number, as long as this call succeeds, and then incrementing
  46 \fIdest\fP by one and \fI*src\fP by the number of bytes consumed.
  47 The
  48 conversion can stop for three reasons:
  49 .PP
  50 1. An invalid multibyte sequence has been encountered.
  51 In this case \fI*src\fP
  52 is left pointing to the invalid multibyte sequence,
  53 .I (size_t)(\-1)
  54 is returned,
  55 and \fIerrno\fP is set to \fBEILSEQ\fP.
  56 .PP
  57 2. The \fInms\fP limit forces a stop, or \fIlen\fP non-L'\\0' wide characters
  58 have been stored at \fIdest\fP.
  59 In this case \fI*src\fP is left pointing to the
  60 next multibyte sequence to be converted, and the number of wide characters
  61 written to \fIdest\fP is returned.
  62 .PP
  63 3. The multibyte string has been completely converted, including the
  64 terminating '\\0' (which has the side effect of bringing back \fI*ps\fP to the
  65 initial state).
  66 In this case \fI*src\fP is set to NULL, and the number of wide
  67 characters written to \fIdest\fP, excluding the terminating L'\\0' character,
  68 is returned.
  69 .PP
  70 If \fIdest\fP is NULL, \fIlen\fP is ignored, and the conversion proceeds as
  71 above, except that the converted wide characters
  72 are not written out to memory,
  73 and that no destination length limit exists.
  74 .PP
  75 In both of the above cases, if \fIps\fP is a NULL pointer, a static anonymous
  76 state only known to the mbsnrtowcs function is used instead.
  77 .PP
  78 The programmer must ensure that there is room for at least \fIlen\fP wide
  79 characters at \fIdest\fP.
  80 .SH "RETURN VALUE"
  81 The
  82 .BR mbsnrtowcs ()
  83 function returns the number of wide characters
  84 that make up the converted part of the wide-character string,
  85 not including the terminating null wide character.
  86 If an invalid multibyte sequence was
  87 encountered,
  88 .I (size_t)(\-1)
  89 is returned, and \fIerrno\fP set to \fBEILSEQ\fP.
  90 .SH "CONFORMING TO"
  91 This function is a GNU extension.
  92 .SH NOTES
  93 The behavior of
  94 .BR mbsnrtowcs ()
  95 depends on the
  96 .B LC_CTYPE
  97 category of the
  98 current locale.
  99 .PP
 100 Passing NULL as \fIps\fP is not multi-thread safe.
 101 .SH "SEE ALSO"
 102 .BR iconv (3),
 103 .BR mbsrtowcs (3)