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$FreeBSD: src/lib/libc/locale/mbrtowc.3,v 1.5 2004/06/30 19:32:41 ru Exp $
.Dd April 8, 2004 .Dt MBRTOWC 3 .Os .Sh NAME .Nm mbrtowc , .Nm mbrtowc_l .Nd "convert a character to a wide-character code (restartable)" .Sh LIBRARY .Lb libc .Sh SYNOPSIS n wchar.h .Ft size_t .Fo mbrtowc .Fa "wchar_t *restrict pwc" .Fa "const char *restrict s" .Fa "size_t n" .Fa "mbstate_t *restrict ps" .Fc n wchar.h n xlocale.h .Ft size_t .Fo mbrtowc_l .Fa "wchar_t *restrict pwc" .Fa "const char *restrict s" .Fa "size_t n" .Fa "mbstate_t *restrict ps" .Fa "locale_t loc" .Fc .Sh DESCRIPTION The .Fn mbrtowc function inspects at most .Fa n bytes, pointed to by .Fa s , to determine the number of bytes needed to complete the next multibyte character. If a character can be completed, and .Fa pwc is not .Dv NULL , the wide character which is represented by .Fa s is stored in the .Vt wchar_t it points to.
p If .Fa s is .Dv NULL , .Fn mbrtowc behaves as if .Fa pwc were .Dv NULL , .Fa s were an empty string
q Qq , and .Fa n were 1.
p The .Vt mbstate_t argument, .Fa ps , is used to keep track of the shift state. If it is .Dv NULL , .Fn mbrtowc uses an internal, static .Vt mbstate_t object, which is initialized to the initial conversion state at program startup.
p While the .Fn mbrtowc function uses the current locale, the .Fn mbrtowc_l function may be passed a locale directly. See .Xr xlocale 3 for more information. .Sh RETURN VALUES The .Fn mbrtowc functions returns: l -tag -width indent t 0 The next .Fa n or fewer bytes represent the null wide character
q Li "L'\e0'" . t >0 The next .Fa n or fewer bytes represent a valid character, .Fn mbrtowc returns the number of bytes used to complete the multibyte character. t Po Vt size_t Pc Ns -2 The next .Fa n contribute to, but do not complete, a valid multibyte character sequence, and all .Fa n bytes have been processed. t Po Vt size_t Pc Ns -1 An encoding error has occurred. The next .Fa n or fewer bytes do not contribute to a valid multibyte character. .El .Sh ERRORS The .Fn mbrtowc function will fail if: l -tag -width Er t Bq Er EILSEQ An invalid multibyte sequence was detected. t Bq Er EINVAL The conversion state is invalid. .El .Sh SEE ALSO .Xr mbtowc 3 , .Xr multibyte 3 , .Xr setlocale 3 , .Xr wcrtomb 3 , .Xr xlocale 3 .Sh STANDARDS The .Fn mbrtowc function conforms to .St -isoC-99 .