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: head/lib/libc/locale/mbrlen.3 131360 2004-06-30 19:32:41Z ru $ 26.\" 27.Dd December 26, 2013 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.Fn mbrlen "const char * restrict s" "size_t n" "mbstate_t * restrict ps" 40.In xlocale.h 41.Ft size_t 42.Fn mbrlen_l "const char * restrict s" "size_t n" "mbstate_t * restrict ps" "locale_t locale" 43.Sh DESCRIPTION 44The 45.Fn mbrlen 46and 47.Fn mbrlen_l 48functions inspect at most 49.Fa n 50bytes pointed to by 51.Fa s 52to determine the number of bytes needed to complete the next 53multibyte character. 54.Pp 55The 56.Vt mbstate_t 57argument, 58.Fa ps , 59is used to keep track of the shift state. 60If it is 61.Dv NULL , 62.Fn mbrlen 63and 64.Fn mbrlen_l 65use an internal, static 66.Vt mbstate_t 67object, which is initialized to the initial conversion state 68at program startup. 69.Pp 70It is equivalent to: 71.Pp 72.Dl "mbrtowc(NULL, s, n, ps);" 73.Pp 74Except that when 75.Fa ps 76is a 77.Dv NULL 78pointer, 79.Fn mbrlen 80and 81.Fn mbrlen_l 82use their own static, internal 83.Vt mbstate_t 84object to keep track of the shift state. 85.Pp 86The 87.Fn mbrlen_l 88function takes an explicit 89.Fa locale 90argument, whereas the 91.Fn mbrlen 92function uses the current global or per-thread locale. 93.Sh RETURN VALUES 94The 95.Fn mbrlen 96and 97.Fn mbrlen_l 98functions return: 99.Bl -tag -width indent 100.It 0 101The next 102.Fa n 103or fewer bytes 104represent the null wide character 105.Pq Li "L'\e0'" . 106.It >0 107The next 108.Fa n 109or fewer bytes 110represent a valid character, 111.Fn mbrlen 112and 113.Fn mbrlen_l 114return the number of bytes used to complete the multibyte character. 115.It Po Vt size_t Pc Ns \-2 116The next 117.Fa n 118contribute to, but do not complete, a valid multibyte character sequence, 119and all 120.Fa n 121bytes have been processed. 122.It Po Vt size_t Pc Ns \-1 123An encoding error has occurred. 124The next 125.Fa n 126or fewer bytes do not contribute to a valid multibyte character. 127.El 128.Sh EXAMPLES 129A function that calculates the number of characters in a multibyte 130character string: 131.Bd -literal -offset indent 132size_t 133nchars(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 150The 151.Fn mbrlen 152and 153.Fn mbrlen_l 154functions will fail if: 155.Bl -tag -width Er 156.It Bq Er EILSEQ 157An invalid multibyte sequence was detected. 158.It Bq Er EINVAL 159The conversion state is invalid. 160.El 161.Sh SEE ALSO 162.Xr mblen 3 , 163.Xr mbrtowc 3 , 164.Xr multibyte 3 , 165.Xr xlocale 3 166.Sh STANDARDS 167The 168.Fn mbrlen 169function conforms to 170.St -isoC-99 . 171