locale/FreeBSD/mbrlen.3

   1 .\" Copyright (c) 2002-2004 Tim J. Robbins
   2 .\" All rights reserved.
   3 .\"
   4 .\" Redistribution and use in source and binary forms, with or without
   5 .\" modification, are permitted provided that the following conditions
   6 .\" are met:
   7 .\" 1. Redistributions of source code must retain the above copyright
   8 .\"    notice, this list of conditions and the following disclaimer.
   9 .\" 2. Redistributions in binary form must reproduce the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer in the
  11 .\"    documentation and/or other materials provided with the distribution.
  12 .\"
  13 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  17 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23 .\" SUCH DAMAGE.
  24 .\"
  25 .\" $FreeBSD: src/lib/libc/locale/mbrlen.3,v 1.8 2004/06/30 19:32:41 ru Exp $
  26 .\"
  27 .Dd April 7, 2004
  28 .Dt MBRLEN 3
  29 .Os
  30 .Sh NAME
  31 .Nm mbrlen ,
  32 .Nm mbrlen_l
  33 .Nd "get number of bytes in a character (restartable)"
  34 .Sh LIBRARY
  35 .Lb libc
  36 .Sh SYNOPSIS
  37 .In wchar.h
  38 .Ft size_t
  39 .Fo mbrlen
  40 .Fa "const char *restrict s"
  41 .Fa "size_t n"
  42 .Fa "mbstate_t *restrict ps"
  43 .Fc
  44 .In wchar.h
  45 .In xlocale.h
  46 .Ft size_t
  47 .Fo mbrlen_l
  48 .Fa "const char *restrict s"
  49 .Fa "size_t n"
  50 .Fa "mbstate_t *restrict ps"
  51 .Fa "locale_t loc"
  52 .Fc
  53 .Sh DESCRIPTION
  54 The
  55 .Fn mbrlen
  56 function inspects at most
  57 .Fa n
  58 bytes, pointed to by
  59 .Fa s ,
  60 to determine the number of bytes needed to complete the next
  61 multibyte character.
  62 .Pp
  63 The
  64 .Vt mbstate_t
  65 argument,
  66 .Fa ps ,
  67 is used to keep track of the shift state.
  68 If it is
  69 .Dv NULL ,
  70 .Fn mbrlen
  71 uses an internal, static
  72 .Vt mbstate_t
  73 object, which is initialized to the initial conversion state
  74 at program startup.
  75 .Pp
  76 It is equivalent to:
  77 .Pp
  78 .Dl "mbrtowc(NULL, s, n, ps);"
  79 .Pp
  80 Except that, when
  81 .Fa ps
  82 is a
  83 .Dv NULL
  84 pointer,
  85 .Fn mbrlen
  86 uses its own static, internal
  87 .Vt mbstate_t
  88 object to keep track of the shift state.
  89 .Pp
  90 Although the
  91 .Fn mbrlen
  92 function uses the current locale, the
  93 .Fn mbrlen_l
  94 function may be passed a locale directly. See
  95 .Xr xlocale 3
  96 for more information.
  97 .Sh RETURN VALUES
  98 The
  99 .Fn mbrlen
 100 functions returns:
 101 .Bl -tag -width indent
 102 .It 0
 103 The next
 104 .Fa n
 105 or fewer bytes
 106 represent the null wide character
 107 .Pq Li "L'\e0'" .
 108 .It >0
 109 The next
 110 .Fa n
 111 or fewer bytes
 112 represent a valid character,
 113 .Fn mbrlen
 114 returns the number of bytes used to complete the multibyte character.
 115 .It Po Vt size_t Pc Ns \-2
 116 The next
 117 .Fa n
 118 contribute to, but do not complete, a valid multibyte character sequence,
 119 and all
 120 .Fa n
 121 bytes have been processed.
 122 .It Po Vt size_t Pc Ns \-1
 123 An encoding error has occurred.
 124 The next
 125 .Fa n
 126 or fewer bytes do not contribute to a valid multibyte character.
 127 .El
 128 .Sh EXAMPLES
 129 A function that calculates the number of characters in a multibyte
 130 character string:
 131 .Bd -literal -offset indent
 132 size_t
 133 nchars(const char *s)
 134 {
 135         size_t charlen, chars;
 136         mbstate_t mbs;
 137
 138         chars = 0;
 139         memset(&mbs, 0, sizeof(mbs));
 140         while ((charlen = mbrlen(s, MB_CUR_MAX, &mbs)) != 0 &&
 141             charlen != (size_t)-1 && charlen != (size_t)-2) {
 142                 s += charlen;
 143                 chars++;
 144         }
 145
 146         return (chars);
 147 }
 148 .Ed
 149 .Sh ERRORS
 150 The
 151 .Fn mbrlen
 152 function will fail if:
 153 .Bl -tag -width Er
 154 .It Bq Er EILSEQ
 155 An invalid multibyte sequence was detected.
 156 .It Bq Er EINVAL
 157 The conversion state is invalid.
 158 .El
 159 .Sh SEE ALSO
 160 .Xr mblen 3 ,
 161 .Xr mbrtowc 3 ,
 162 .Xr multibyte 3 ,
 163 .Xr xlocale 3
 164 .Sh STANDARDS
 165 The
 166 .Fn mbrlen
 167 function conforms to
 168 .St -isoC-99 .