.\" $NetBSD: mbsrtowcs.3,v 1.4 2002/10/01 17:02:57 wiz Exp $
.\"
.\" Copyright (c)2002 Citrus Project,
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.Dd February 4, 2002
.Dt MBSRTOWCS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm mbsrtowcs
.Nd converts a multibyte character string to a wide character string \
(restartable)
.\" ----------------------------------------------------------------------
.Sh LIBRARY
.Lb libc
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include \*[Lt]wchar.h\*[Gt]
.Ft size_t
.Fn mbsrtowcs "wchar_t * restrict pwcs" "const char ** restrict s" "size_t n" \
"mbstate_t * restrict ps"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
The
.Fn mbsrtowcs
converts the multibyte character string indirectly pointed by
.Fa s
to the corresponding wide character string, and stores it to the
array pointed by
.Fa pwcs .
The conversion stops due to the following reasons:
.Bl -bullet
.It
The conversion reaches a null byte.
In this case, the null byte is also converted.
.It
The
.Fn mbsrtowcs
has already stored
.Fa n
wide characters.
.It
The conversion encounters an invalid character.
.El
.Pp
Each characters will be converted as if
.Xr mbrtowc 3
is continuously called.
.Pp
After conversion,
if
.Fa pwcs
is not NULL pointer,
the pointer object pointed by
.Fa s
is NULL pointer (if the conversion is stopped due to reach a null byte)
or the first byte of the character just after the last character converted.
.Pp
If
.Fa pwcs
is not null pointer and the conversion is stopped due to reach
a null byte, the
.Fn mbsrtowcs
places the state object pointed by
.Fa ps
to an initial state after the conversion is taken place.
.Pp
The behaviour of the
.Fn mbsrtowcs
is affected by LC_CTYPE category of the current locale.
.Pp
There are special cases:
.Bl -tag -width 012345678901
.It "s == NULL || *s == NULL"
undefined (may causes the program to crash).
.It "pwcs == NULL"
The conversion is taken place, but the result wide character string
is discarded.
In this case, the pointer object pointed by
.Fa s
is not modified and
.Fa n
is ignored.
.It "ps == NULL"
The
.Fn mbsrtowcs
uses its own internal state object to keep the conversion state,
instead of
.Fa ps
mentioned in this manual page.
.Pp
Calling any other functions in the
.Lb libc
never change the internal
state of the
.Fn mbsrtowcs ,
that is initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
The
.Fn mbsrtowcs
returns
.Bl -tag -width 012345678901
.It 0 or positive
The value returned is the number of elements stored to the array pointed by
.Fa pwcs ,
except for a terminate null wide character (if any).
If
.Fa pwcs
is not null and the value returned is equal to
.Fa n ,
the wide character string pointed by
.Fa pwcs
is not null terminated.
If
.Fa pwcs
is a null pointer, the value returned is the number of elements to contain
the whole string converted, except for a terminate null wide character.
.It (size_t)-1
The array indirectly pointed by
.Fa s
contains a byte sequence forming invalid character.
In this case, the
.Fn mbsrtowcs
sets errno to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
The
.Fn mbsrtowcs
may causes an error in the following case:
.Bl -tag -width Er
.It Bq Er EILSEQ
The pointer pointed by
.Fa s
points an invalid or incomplete multibyte character.
.It Bq Er EINVAL
.Fa ps
points an invalid or uninitialized mbstate_t object.
.El
.\" ----------------------------------------------------------------------
.Sh SEE ALSO
.Xr mbrtowc 3 ,
.Xr mbstowcs 3 ,
.Xr setlocale 3
.\" ----------------------------------------------------------------------
.Sh STANDARDS
The
.Fn mbsrtowcs
function conforms to
.St -isoC-amd1 .
The restrict qualifier is added at
.St -isoC99 .