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$FreeBSD: head/lib/libc/locale/mbrtowc.3 102050 2002-08-18 06:30:10Z tjr $
.Dd August 15, 2002 .Dt MBRTOWC 3 .Os .Sh NAME .Nm mbrtowc .Nd "convert a character to a wide-character code (restartable)" .Sh LIBRARY .Lb libc .Sh SYNOPSIS n wchar.h .Ft size_t .Fn mbrtowc "wchar_t *restrict pwc" "const char *restrict s" "size_t n" "mbstate_t *restrict ps" .Sh DESCRIPTION The .Fn mbrtowc function inspects at most .Fa n bytes pointed to by .Fa s and interprets them as a multibyte character sequence according to the current setting of .Ev LC_CTYPE . If .Fa pwc is not .Dv NULL , the multibyte character which .Fa s represents is stored in the .Ft wchar_t it points to.
p If .Fa s is .Dv NULL , .Fn mbrtowc behaves as if .Fa pwc was .Dv NULL , .Fa s was an empty string ("") and .Fa n was 1.
p
The
.Ft 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
.Ft mbstate_t
object.
.Sh RETURN VALUES
The
.Fn mbrtowc
functions returns:
l -tag -width indent t 0 The first
.Fa n
or fewer bytes of
.Fa s
represent the null wide character (L'\e0').
t >0 The first
.Fa n
or fewer bytes of
.Fa s
represent a valid character,
.Fn mbrtowc
returns the length (in bytes) of the multibyte sequence.
t Xo .No ( Ns
.Ft size_t Ns
.No ) Ns -2
.Xc
The first
.Fa n
bytes of
.Fa s
are an incomplete multibyte sequence.
t Xo .No ( Ns
.Ft size_t Ns
.No ) Ns -1
.Xc
The byte sequence pointed to by
.Fa s
is an invalid multibyte sequence.
.El
.Sh ERRORS
The
.Fn mbrtowc
function will fail if:
l -tag -width Er .It Bq Er EINVAL
Invalid argument.
t Bq Er EILSEQ An invalid multibyte sequence was detected.
.El
.Sh SEE ALSO
.Xr mbtowc 3 ,
.Xr setlocale 3 ,
.Xr wcrtomb 3
.Sh STANDARDS
The
.Fn mbrtowc
function conforms to
.St -isoC-99 .
.Sh BUGS
The current implementation does not support shift states.