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.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\" and Copyright 2014 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\" Modified Sat Jul 24 17:45:39 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified 2000-02-13 by Nicolás Lichtmaier <nick@debian.org>
.TH TOUPPER 3 2014-03-18 "GNU" "Linux Programmer's Manual"
.SH NAME
toupper, tolower, toupper_l, tolower_l \- convert uppercase or lowercase
.SH SYNOPSIS
.nf
.B #include <ctype.h>
.sp
.BI "int toupper(int " "c" );
.br
.BI "int tolower(int " "c" );
.BI "int toupper_l(int " c ", locale_t " locale );
.BI "int tolower_l(int " c ", locale_t " locale );
.fi
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR toupper_l (),
.BR tolower_l ():
.PD 0
.RS 4
.TP
Since glibc 2.10:
_XOPEN_SOURCE\ >=\ 700
.TP
Before glibc 2.10:
_GNU_SOURCE
.RE
.PD
.SH DESCRIPTION
These functions convert lowercase letters to uppercase, and vice versa.
If
.I c
is a lowercase letter,
.BR toupper ()
returns its uppercase equivalent,
if an uppercase representation exists in the current locale.
Otherwise, it returns
.IR c .
The
.BR toupper_l ()
function performs the same task,
but uses the locale referred to by the locale handle
.IR locale .
If
.I c
is a uppercase letter,
.BR tolower ()
returns its lowercase equivalent,
if a lowercase representation exists in the current locale.
Otherwise, it returns
.IR c .
The
.BR tolower_l ()
function performs the same task,
but uses the locale referred to by the locale handle
.IR locale .
.PP
If
.I c
is neither an
.I "unsigned char"
value nor
.BR EOF ,
the behavior of these functions
is undefined.
The behavior of
.BR toupper_l ()
and
.BR tolower_l ()
is undefined if
.I locale
is the special locale object
.BR LC_GLOBAL_LOCALE
(see
.BR duplocale (3))
or is not a valid locale object handle.
.SH RETURN VALUE
The value returned is that of the converted letter, or
.I c
if the conversion was not possible.
.SH ATTRIBUTES
.SS Multithreading (see pthreads(7))
The
.BR toupper ()
and
.BR tolower ()
functions are thread-safe with exceptions.
These functions can be safely used in multithreaded applications,
as long as
.BR setlocale (3)
is not called to change the locale during their execution.
.\" FIXME . Add toupper_l() and tolower_l()
.SH CONFORMING TO
.BR toupper (),
.BR tolower ():
C89, C99, 4.3BSD, POSIX.1-2001, POSIX.1-2008.
.BR toupper_l (),
.BR tolower_l ():
POSIX.1-2008.
.SH NOTES
The details of what constitutes an uppercase or lowercase letter depend
on the locale.
For example, the default
.B """C"""
locale does not know about umlauts, so no conversion is done for them.
.PP
In some non-English locales, there are lowercase letters with no
corresponding uppercase equivalent;
.\" FIXME One day the statement about "sharp s" needs to be reworked,
.\" since there is nowadays a capital "sharp s" that has a codepoint
.\" in Unicode 5.0; see https://en.wikipedia.org/wiki/Capital_%E1%BA%9E
the German sharp s is one example.
.SH SEE ALSO
.BR isalpha (3),
.BR newlocale (3),
.BR setlocale (3),
.BR uselocale (3),
.BR towlower (3),
.BR towupper (3),
.BR locale (7)
.SH COLOPHON
This page is part of release 3.74 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%http://www.kernel.org/doc/man\-pages/.
|
