NetBSD/lib/libc/locale/wcstombs.3

.\" $NetBSD: wcstombs.3,v 1.5 2003/09/08 17:54:32 wiz Exp $
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.Dd February 4, 2002
.Dt WCSTOMBS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm wcstombs
.Nd converts a wide character string to a multibyte character string
.\" ----------------------------------------------------------------------
.Sh LIBRARY
.Lb libc
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.In stdlib.h
.Ft size_t
.Fn wcstombs "const char * restrict s" "wchar_t * restrict pwcs" "size_t n"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
The
.Fn wcstombs
converts the null-terminated wide character string pointed by
.Fa pwcs
to the corresponding multibyte character string,
and store it to the array pointed by
.Fa s .
This function may modify the first at most
.Fa n
bytes of the array pointed by
.Fa s .
Each characters will be converted as if
.Xr wctomb 3
is continuously called, except the internal state of
.Xr wctomb 3
will not be affected.
.Pp
For state-dependent encoding, the
.Fn wcstombs
implies the result multibyte character string pointed by
.Fa s
always to begin with an initial state.
.Pp
The behaviour of the
.Fn wcstombs
is affected by LC_CTYPE category of the current locale.
.Pp
There are special cases:
.Bl -tag -width 012345678901
.It s == NULL
The
.Fn wcstombs
returns the number of bytes to store the whole multibyte character string
corresponding to the wide character string pointed by
.Fa pwcs .
In this case,
.Fa n
is ignored.
.It pwcs == NULL
undefined (may causes the program to crash).
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
The
.Fn wcstombs
returns:
.Bl -tag -width 012345678901
.It 0 or positive
number of bytes stored to the array pointed by
.Fa s .
There is no cases that the value returned is greater than
.Fa n
(unless
.Fa s
is a null pointer).
If the return value is equal to
.Fa n ,
the string pointed by
.Fa s
will not be null-terminated.
.It (size_t)-1
.Fa pwcs
points the string containing invalid wide character.
The
.Fn wcstombs
also sets errno to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
The
.Fn wcstombs
may causes an error in the following case:
.Bl -tag -width Er
.It Bq Er EILSEQ
.Fa pwcs
points the string containing invalid wide character.
.El
.\" ----------------------------------------------------------------------
.Sh SEE ALSO
.Xr setlocale 3 ,
.Xr wctomb 3
.\" ----------------------------------------------------------------------
.Sh STANDARDS
The
.Fn wcstombs
function conforms to
.St -ansiC .
The restrict qualifier is added at
.St -isoC-99 .