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[thirdparty/man-pages.git] / man3 / towlower.3

.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" References consulted:
.\"   GNU glibc-2 source code and manual
.\"   Dinkumware C library reference http://www.dinkumware.com/
.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
.\"   ISO/IEC 9899:1999
.\"
.TH towlower 3 (date) "Linux man-pages (unreleased)"
.SH NAME
towlower, towlower_l \- convert a wide character to lowercase
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <wctype.h>
.PP
.BI "wint_t towlower(wint_t " wc );
.BI "wint_t towlower_l(wint_t " wc ", locale_t " locale );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR towlower_l ():
.nf
    Since glibc 2.10:
        _XOPEN_SOURCE >= 700
    Before glibc 2.10:
        _GNU_SOURCE
.fi
.SH DESCRIPTION
The
.BR towlower ()
function is the wide-character equivalent of the
.BR tolower (3)
function.
If
.I wc
is an uppercase wide character,
and there exists a lowercase equivalent in the current locale,
it returns the lowercase equivalent of
.IR wc .
In all other cases,
.I wc
is returned unchanged.
.PP
The
.BR towlower_l ()
function performs the same task,
but performs the conversion based on the character type information in
the locale specified by
.IR locale .
The behavior of
.BR towlower_l ()
is undefined if
.I locale
is the special locale object
.B LC_GLOBAL_LOCALE
(see
.BR duplocale (3))
or is not a valid locale object handle.
.PP
The argument
.I wc
must be representable as a
.I wchar_t
and be a valid character in the locale or be the value
.BR WEOF .
.SH RETURN VALUE
If
.I wc
was convertible to lowercase,
.BR towlower ()
returns its lowercase equivalent;
otherwise it returns
.IR wc .
.SH VERSIONS
The
.BR towlower_l ()
function first appeared in glibc 2.3.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR towlower ()
T}	Thread safety	MT-Safe locale
T{
.BR towlower_l ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
.BR towlower ():
C99, POSIX.1-2001 (XSI);
present as an XSI extension in POSIX.1-2008, but marked obsolete.
.PP
.BR towlower_l ():
POSIX.1-2008.
.SH NOTES
The behavior of these functions depends on the
.B LC_CTYPE
category of the locale.
.PP
These functions are not very appropriate for dealing with Unicode characters,
because Unicode knows about three cases: upper, lower, and title case.
.SH SEE ALSO
.BR iswlower (3),
.BR towctrans (3),
.BR towupper (3),
.BR locale (7)