locale/FreeBSD/mbrtowc.3

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  25 .\" $FreeBSD: src/lib/libc/locale/mbrtowc.3,v 1.5 2004/06/30 19:32:41 ru Exp $
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  27 .Dd April 8, 2004
  28 .Dt MBRTOWC 3
  29 .Os
  30 .Sh NAME
  31 .Nm mbrtowc ,
  32 .Nm mbrtowc_l
  33 .Nd "convert a character to a wide-character code (restartable)"
  34 .Sh LIBRARY
  35 .Lb libc
  36 .Sh SYNOPSIS
  37 .In wchar.h
  38 .Ft size_t
  39 .Fo mbrtowc
  40 .Fa "wchar_t *restrict pwc"
  41 .Fa "const char *restrict s"
  42 .Fa "size_t n"
  43 .Fa "mbstate_t *restrict ps"
  44 .Fc
  45 .In wchar.h
  46 .In xlocale.h
  47 .Ft size_t
  48 .Fo mbrtowc_l
  49 .Fa "wchar_t *restrict pwc"
  50 .Fa "const char *restrict s"
  51 .Fa "size_t n"
  52 .Fa "mbstate_t *restrict ps"
  53 .Fa "locale_t loc"
  54 .Fc
  55 .Sh DESCRIPTION
  56 The
  57 .Fn mbrtowc
  58 function inspects at most
  59 .Fa n
  60 bytes, pointed to by
  61 .Fa s ,
  62 to determine the number of bytes needed to complete the next multibyte
  63 character.
  64 If a character can be completed, and
  65 .Fa pwc
  66 is not
  67 .Dv NULL ,
  68 the wide character which is represented by
  69 .Fa s
  70 is stored in the
  71 .Vt wchar_t
  72 it points to.
  73 .Pp
  74 If
  75 .Fa s
  76 is
  77 .Dv NULL ,
  78 .Fn mbrtowc
  79 behaves as if
  80 .Fa pwc
  81 were
  82 .Dv NULL ,
  83 .Fa s
  84 were an empty string
  85 .Pq Qq ,
  86 and
  87 .Fa n
  88 were 1.
  89 .Pp
  90 The
  91 .Vt mbstate_t
  92 argument,
  93 .Fa ps ,
  94 is used to keep track of the shift state.
  95 If it is
  96 .Dv NULL ,
  97 .Fn mbrtowc
  98 uses an internal, static
  99 .Vt mbstate_t
 100 object, which is initialized to the initial conversion state
 101 at program startup.
 102 .Pp
 103 While the
 104 .Fn mbrtowc
 105 function uses the current locale, the
 106 .Fn mbrtowc_l
 107 function may be passed a locale directly. See
 108 .Xr xlocale 3
 109 for more information.
 110 .Sh RETURN VALUES
 111 The
 112 .Fn mbrtowc
 113 functions returns:
 114 .Bl -tag -width indent
 115 .It 0
 116 The next
 117 .Fa n
 118 or fewer bytes
 119 represent the null wide character
 120 .Pq Li "L'\e0'" .
 121 .It >0
 122 The next
 123 .Fa n
 124 or fewer bytes
 125 represent a valid character,
 126 .Fn mbrtowc
 127 returns the number of bytes used to complete the multibyte character.
 128 .It Po Vt size_t Pc Ns \-2
 129 The next
 130 .Fa n
 131 contribute to, but do not complete, a valid multibyte character sequence,
 132 and all
 133 .Fa n
 134 bytes have been processed.
 135 .It Po Vt size_t Pc Ns \-1
 136 An encoding error has occurred.
 137 The next
 138 .Fa n
 139 or fewer bytes do not contribute to a valid multibyte character.
 140 .El
 141 .Sh ERRORS
 142 The
 143 .Fn mbrtowc
 144 function will fail if:
 145 .Bl -tag -width Er
 146 .It Bq Er EILSEQ
 147 An invalid multibyte sequence was detected.
 148 .It Bq Er EINVAL
 149 The conversion state is invalid.
 150 .El
 151 .Sh SEE ALSO
 152 .Xr mbtowc 3 ,
 153 .Xr multibyte 3 ,
 154 .Xr setlocale 3 ,
 155 .Xr wcrtomb 3 ,
 156 .Xr xlocale 3
 157 .Sh STANDARDS
 158 The
 159 .Fn mbrtowc
 160 function conforms to
 161 .St -isoC-99 .