freebsd-nq/lib/libc/string/wcsxfrm.3

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.\"     @(#)strxfrm.3	8.1 (Berkeley) 6/4/93
.\" FreeBSD: src/lib/libc/string/strxfrm.3,v 1.16 2002/09/06 11:24:06 tjr Exp
.\" $FreeBSD$
.\"
.Dd October 4, 2002
.Dt WCSXFRM 3
.Os
.Sh NAME
.Nm wcsxfrm
.Nd transform a wide string under locale
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft size_t
.Fn wcsxfrm "wchar_t * restrict dst" "const wchar_t * restrict src" "size_t n"
.Sh DESCRIPTION
The
.Fn wcsxfrm
function transforms a null-terminated wide character string pointed to by
.Fa src
according to the current locale collation order
then copies the transformed string
into
.Fa dst .
No more than
.Fa n
wide characters are copied into
.Fa dst ,
including the terminating null character added.
If
.Fa n
is set to 0
(it helps to determine an actual size needed
for transformation),
.Fa dst
is permitted to be a
.Dv NULL
pointer.
.Pp
Comparing two strings using
.Fn wcscmp
after
.Fn wcsxfrm
is equivalent to comparing
two original strings with
.Fn wcscoll .
.Sh RETURN VALUES
Upon successful completion,
.Fn wcsxfrm
returns the length of the transformed string not including
the terminating null character.
If this value is
.Fa n
or more, the contents of
.Fa dst
are indeterminate.
.Sh SEE ALSO
.Xr setlocale 3 ,
.Xr strxfrm 3 ,
.Xr wcscmp 3 ,
.Xr wcscoll 3
.Sh STANDARDS
The
.Fn wcsxfrm
function
conforms to
.St -isoC-99 .
.Sh BUGS
The current implementation of
.Fn wcsxfrm
only works in single-byte
.Dv LC_CTYPE
locales, and falls back to using
.Fn wcsncpy
in locales with extended character sets.
.Pp
Comparing two strings using
.Fn wcscmp
after
.Fn wcsxfrm
is
.Em not
always equivalent to comparison with
.Fn wcscoll ;
.Fn wcsxfrm
only stores information about primary collation weights into
.Fa dst ,
whereas
.Fn wcscoll
compares characters using both primary and secondary weights.