man3/wcstombs.3

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  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 WCSTOMBS 3  2019-03-06 "GNU" "Linux Programmer's Manual"
  17 .SH NAME
  18 wcstombs \- convert a wide-character string to a multibyte string
  19 .SH SYNOPSIS
  20 .nf
  21 .B #include <stdlib.h>
  22 .PP
  23 .BI "size_t wcstombs(char *" dest ", const wchar_t *" src ", size_t " n );
  24 .fi
  25 .SH DESCRIPTION
  26 If
  27 .I dest
  28 is not NULL, the
  29 .BR wcstombs ()
  30 function converts
  31 the wide-character string
  32 .I src
  33 to a multibyte string starting at
  34 .IR dest .
  35 At most
  36 .I n
  37 bytes are written to
  38 .IR dest .
  39 The sequence of characters placed in
  40 .IR dest
  41 begins in the initial shift state.
  42 The conversion can stop for three reasons:
  43 .IP 1. 3
  44 A wide character has been encountered that can not be represented as a
  45 multibyte sequence (according to the current locale).
  46 In this case,
  47 .I (size_t)\ \-1
  48 is returned.
  49 .IP 2.
  50 The length limit forces a stop.
  51 In this case, the number of bytes written to
  52 .I dest
  53 is returned, but the shift state at this point is lost.
  54 .IP 3.
  55 The wide-character string has been completely converted, including the
  56 terminating null wide character (L\(aq\e0\(aq).
  57 In this case, the conversion ends in the initial shift state.
  58 The number of bytes written to
  59 .IR dest ,
  60 excluding the terminating null byte (\(aq\e0\(aq), is returned.
  61 .PP
  62 The programmer must ensure that there is room for at least
  63 .I n
  64 bytes
  65 at
  66 .IR dest .
  67 .PP
  68 If
  69 .IR dest
  70 is NULL,
  71 .I n
  72 is ignored, and the conversion proceeds as
  73 above, except that the converted bytes are not written out to memory,
  74 and no length limit exists.
  75 .PP
  76 In order to avoid the case 2 above, the programmer should make sure
  77 .I n
  78 is greater than or equal to
  79 .IR "wcstombs(NULL,src,0)+1" .
  80 .SH RETURN VALUE
  81 The
  82 .BR wcstombs ()
  83 function returns the number of bytes that make up the
  84 converted part of a multibyte sequence,
  85 not including the terminating null byte.
  86 If a wide character was encountered which could not be
  87 converted,
  88 .I (size_t)\ \-1
  89 is returned.
  90 .SH ATTRIBUTES
  91 For an explanation of the terms used in this section, see
  92 .BR attributes (7).
  93 .TS
  94 allbox;
  95 lb lb lb
  96 l l l.
  97 Interface       Attribute       Value
  98 T{
  99 .BR wcstombs ()
 100 T}      Thread safety   MT-Safe
 101 .TE
 102 .sp 1
 103 .SH CONFORMING TO
 104 POSIX.1-2001, POSIX.1-2008, C99.
 105 .SH NOTES
 106 The behavior of
 107 .BR wcstombs ()
 108 depends on the
 109 .B LC_CTYPE
 110 category of the
 111 current locale.
 112 .PP
 113 The function
 114 .BR wcsrtombs (3)
 115 provides a better interface to the same functionality.
 116 .SH SEE ALSO
 117 .BR mblen (3),
 118 .BR mbstowcs (3),
 119 .BR mbtowc (3),
 120 .BR wcsrtombs (3),
 121 .BR wctomb (3)