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 May 21, 2013 28.Dt MBRTOWC 3 29.Os 30.Sh NAME 31.Nm mbrtowc , 32.Nm mbrtoc16 , 33.Nm mbrtoc32 34.Nd "convert a character to a wide-character code (restartable)" 35.Sh LIBRARY 36.Lb libc 37.Sh SYNOPSIS 38.In wchar.h 39.Ft size_t 40.Fo mbrtowc 41.Fa "wchar_t * restrict pc" "const char * restrict s" "size_t n" 42.Fa "mbstate_t * restrict ps" 43.Fc 44.In uchar.h 45.Ft size_t 46.Fo mbrtoc16 47.Fa "char16_t * restrict pc" "const char * restrict s" "size_t n" 48.Fa "mbstate_t * restrict ps" 49.Fc 50.Ft size_t 51.Fo mbrtoc32 52.Fa "char32_t * restrict pc" "const char * restrict s" "size_t n" 53.Fa "mbstate_t * restrict ps" 54.Fc 55.Sh DESCRIPTION 56The 57.Fn mbrtowc , 58.Fn mbrtoc16 59and 60.Fn mbrtoc32 61functions inspect at most 62.Fa n 63bytes pointed to by 64.Fa s 65to determine the number of bytes needed to complete the next multibyte 66character. 67If a character can be completed, and 68.Fa pc 69is not 70.Dv NULL , 71the wide character which is represented by 72.Fa s 73is stored in the 74.Vt wchar_t , 75.Vt char16_t 76or 77.Vt char32_t 78it points to. 79.Pp 80If 81.Fa s 82is 83.Dv NULL , 84these functions behave as if 85.Fa pc 86was 87.Dv NULL , 88.Fa s 89was an empty string 90.Pq Qq 91and 92.Fa n 93was 1. 94.Pp 95The 96.Vt mbstate_t 97argument, 98.Fa ps , 99is used to keep track of the shift state. 100If it is 101.Dv NULL , 102these functions use an internal, static 103.Vt mbstate_t 104object, which is initialized to the initial conversion state 105at program startup. 106.Pp 107As a single 108.Vt char16_t 109is not large enough to represent certain multibyte characters, the 110.Fn mbrtoc16 111function may need to be invoked multiple times to convert a single 112multibyte character sequence. 113.Sh RETURN VALUES 114The 115.Fn mbrtowc , 116.Fn mbrtoc16 117and 118.Fn mbrtoc32 119functions return: 120.Bl -tag -width indent 121.It 0 122The next 123.Fa n 124or fewer bytes 125represent the null wide character 126.Pq Li "L'\e0'" . 127.It >0 128The next 129.Fa n 130or fewer bytes represent a valid character, these functions 131return the number of bytes used to complete the multibyte character. 132.It Po Vt size_t Pc Ns \-1 133An encoding error has occurred. 134The next 135.Fa n 136or fewer bytes do not contribute to a valid multibyte character. 137.It Po Vt size_t Pc Ns \-2 138The next 139.Fa n 140contribute to, but do not complete, a valid multibyte character sequence, 141and all 142.Fa n 143bytes have been processed. 144.El 145.Pp 146The 147.Fn mbrtoc16 148function also returns: 149.Bl -tag -width indent 150.It Po Vt size_t Pc Ns \-3 151The next character resulting from a previous call has been stored. 152No bytes from the input have been consumed. 153.El 154.Sh ERRORS 155The 156.Fn mbrtowc , 157.Fn mbrtoc16 158and 159.Fn mbrtoc32 160functions will fail if: 161.Bl -tag -width Er 162.It Bq Er EILSEQ 163An invalid multibyte sequence was detected. 164.It Bq Er EINVAL 165The conversion state is invalid. 166.El 167.Sh SEE ALSO 168.Xr mbtowc 3 , 169.Xr multibyte 3 , 170.Xr setlocale 3 , 171.Xr wcrtomb 3 172.Sh STANDARDS 173The 174.Fn mbrtowc , 175.Fn mbrtoc16 176and 177.Fn mbrtoc32 178functions conform to 179.St -isoC-2011 . 180