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  10 .TH MBRTOWC 3C "Nov 1, 2003"
  11 .SH NAME
  12 mbrtowc \- convert a character to a wide-character code (restartable)
  13 .SH SYNOPSIS
  14 .LP
  15 .nf
  16 #include <wchar.h>
  17 
  18 \fBsize_t\fR \fBmbrtowc\fR(\fBwchar_t *restrict\fR \fIpwc\fR, \fBconst char *restrict\fR \fIs\fR, \fBsize_t\fR \fIn\fR,
  19      \fBmbstate_t *restrict\fR \fIps\fR);
  20 .fi
  21 
  22 .SH DESCRIPTION
  23 .sp
  24 .LP
  25 If \fIs\fR is a null pointer, the \fBmbrtowc()\fR function is equivalent to the
  26 call:
  27 .sp
  28 .in +2
  29 .nf
  30 mbrtowc(NULL, ``'', 1, ps)
  31 .fi
  32 .in -2
  33 
  34 .sp
  35 .LP
  36 In this case, the values of the arguments \fIpwc\fR and \fIn\fR are ignored.
  37 .sp
  38 .LP
  39 If \fIs\fR is not a null pointer, the \fBmbrtowc()\fR function inspects at most
  40 \fIn\fR bytes beginning at the byte pointed to by  \fIs\fR to determine the
  41 number of bytes needed to complete the next  character (including any shift
  42 sequences).  If the function determines that the next character is completed,
  43 it determines the value of the corresponding wide-character and then, if
  44 \fIpwc\fR is not a null pointer, stores that value in the object pointed to by
  45 \fIpwc\fR. If the corresponding wide-character is the null wide-character, the
  46 resulting state described is the initial conversion state.
  47 .sp
  48 .LP
  49 If \fIps\fR is a null pointer, the \fBmbrtowc()\fR function uses its own
  50 internal \fBmbstate_t\fR object, which is initialized at program startup to the
  51 initial conversion state.   Otherwise, the  \fBmbstate_t\fR object pointed to
  52 by \fIps\fR is used to completely describe the current conversion state of the
  53 associated character sequence. Solaris will behave as if no function defined in
  54 the Solaris Reference Manual calls \fBmbrtowc()\fR.
  55 .sp
  56 .LP
  57 The behavior of this function is affected by the \fBLC_CTYPE\fR category of the
  58 current locale.  See \fBenviron\fR(5).
  59 .SH RETURN VALUES
  60 .sp
  61 .LP
  62 The \fBmbrtowc()\fR function returns the first of the following that applies:
  63 .sp
  64 .ne 2
  65 .na
  66 \fB\fB0\fR\fR
  67 .ad
  68 .RS 17n
  69 If the next \fIn\fR or fewer bytes complete the character that corresponds to
  70 the null wide-character (which is the value stored).
  71 .RE
  72 
  73 .sp
  74 .ne 2
  75 .na
  76 \fB\fBpositive\fR\fR
  77 .ad
  78 .RS 17n
  79 If the next \fIn\fR or fewer bytes complete a valid character (which is the
  80 value stored); the value returned is the number of bytes that complete the
  81 character.
  82 .RE
  83 
  84 .sp
  85 .ne 2
  86 .na
  87 \fB\fB(size_t)\(mi2\fR\fR
  88 .ad
  89 .RS 17n
  90 If the next \fIn\fR bytes contribute to an incomplete but potentially valid
  91 character, and all \fIn\fR bytes have been processed (no value is stored).
  92 When \fIn\fR has at least the value of the \fBMB_CUR_MAX\fR macro, this case
  93 can only occur if  \fIs\fR points at a sequence of redundant shift sequences
  94 (for implementations with state-dependent encodings).
  95 .RE
  96 
  97 .sp
  98 .ne 2
  99 .na
 100 \fB\fB(size_t)\(mi1\fR\fR
 101 .ad
 102 .RS 17n
 103 If an encoding error occurs, in which case the next \fIn\fR or fewer bytes do
 104 not contribute to a complete and valid  character (no value is stored).  In
 105 this case, \fBEILSEQ\fR is stored in \fBerrno\fR and the conversion state is
 106 undefined.
 107 .RE
 108 
 109 .SH ERRORS
 110 .sp
 111 .LP
 112 The \fBmbrtowc()\fR function may fail if:
 113 .sp
 114 .ne 2
 115 .na
 116 \fB\fBEINVAL\fR\fR
 117 .ad
 118 .RS 10n
 119 The \fIps\fR argument points to an object that contains an invalid conversion
 120 state.
 121 .RE
 122 
 123 .sp
 124 .ne 2
 125 .na
 126 \fB\fBEILSEQ\fR\fR
 127 .ad
 128 .RS 10n
 129 Invalid character sequence is detected.
 130 .RE
 131 
 132 .SH ATTRIBUTES
 133 .sp
 134 .LP
 135 See \fBattributes\fR(5) for descriptions of the following attributes:
 136 .sp
 137 
 138 .sp
 139 .TS
 140 box;
 141 c | c
 142 l | l .
 143 ATTRIBUTE TYPE  ATTRIBUTE VALUE
 144 _
 145 Interface Stability     Standard
 146 _
 147 MT-Level        See NOTES below
 148 .TE
 149 
 150 .SH SEE ALSO
 151 .sp
 152 .LP
 153 \fBmbsinit\fR(3C), \fBsetlocale\fR(3C), \fBattributes\fR(5), \fBenviron\fR(5),
 154 \fBstandards\fR(5)
 155 .SH NOTES
 156 .sp
 157 .LP
 158 If \fIps\fR is not a null pointer, \fBmbrtowc()\fR uses the \fBmbstate_t\fR
 159 object pointed to by \fIps\fR and the function can be used safely in
 160 multithreaded applications, as long as \fBsetlocale\fR(3C) is not being called
 161 to change the locale. If \fIps\fR is a null pointer, \fBmbrtowc()\fR uses its
 162 internal \fBmbstate_t\fR object and the function is Unsafe in multithreaded
 163 applications.