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.\" $FreeBSD$ 26.\" 27.Dd April 7, 2004 28.Dt MBRLEN 3 29.Os 30.Sh NAME 31.Nm mbrlen 32.Nd "get number of bytes in a character (restartable)" 33.Sh LIBRARY 34.Lb libc 35.Sh SYNOPSIS 36.In wchar.h 37.Ft size_t 38.Fn mbrlen "const char * restrict s" "size_t n" "mbstate_t * restrict ps" 39.Sh DESCRIPTION 40The 41.Fn mbrlen 42function inspects at most 43.Fa n 44bytes pointed to by 45.Fa s 46to determine the number of bytes needed to complete the next 47multibyte character. 48.Pp 49The 50.Vt mbstate_t 51argument, 52.Fa ps , 53is used to keep track of the shift state. 54If it is 55.Dv NULL , 56.Fn mbrlen 57uses an internal, static 58.Vt mbstate_t 59object, which is initialized to the initial conversion state 60at program startup. 61.Pp 62It is equivalent to: 63.Pp 64.Dl "mbrtowc(NULL, s, n, ps);" 65.Pp 66Except that when 67.Fa ps 68is a 69.Dv NULL 70pointer, 71.Fn mbrlen 72uses its own static, internal 73.Vt mbstate_t 74object to keep track of the shift state. 75.Sh RETURN VALUES 76The 77.Fn mbrlen 78functions returns: 79.Bl -tag -width indent 80.It 0 81The next 82.Fa n 83or fewer bytes 84represent the null wide character 85.Pq Li "L'\e0'" . 86.It >0 87The next 88.Fa n 89or fewer bytes 90represent a valid character, 91.Fn mbrlen 92returns the number of bytes used to complete the multibyte character. 93.It Po Vt size_t Pc Ns \-2 94The next 95.Fa n 96contribute to, but do not complete, a valid multibyte character sequence, 97and all 98.Fa n 99bytes have been processed. 100.It Po Vt size_t Pc Ns \-1 101An encoding error has occurred. 102The next 103.Fa n 104or fewer bytes do not contribute to a valid multibyte character. 105.El 106.Sh EXAMPLES 107A function that calculates the number of characters in a multibyte 108character string: 109.Bd -literal -offset indent 110size_t 111nchars(const char *s) 112{ 113 size_t charlen, chars; 114 mbstate_t mbs; 115 116 chars = 0; 117 memset(&mbs, 0, sizeof(mbs)); 118 while ((charlen = mbrlen(s, MB_CUR_MAX, &mbs)) != 0 && 119 charlen != (size_t)-1 && charlen != (size_t)-2) { 120 s += charlen; 121 chars++; 122 } 123 124 return (chars); 125} 126.Ed 127.Sh ERRORS 128The 129.Fn mbrlen 130function will fail if: 131.Bl -tag -width Er 132.It Bq Er EILSEQ 133An invalid multibyte sequence was detected. 134.It Bq Er EINVAL 135The conversion state is invalid. 136.El 137.Sh SEE ALSO 138.Xr mblen 3 , 139.Xr mbrtowc 3 , 140.Xr multibyte 3 141.Sh STANDARDS 142The 143.Fn mbrlen 144function conforms to 145.St -isoC-99 . 146