Name
toupper, tolower, toupper_l, tolower_l — convert uppercase or lowercase
Synopsis
#include <ctype.h>
int
toupper( |
int c); |
int
tolower( |
int c); |
int
toupper_l( |
int c, |
locale_t locale); |
int
tolower_l( |
int c, |
locale_t locale); |
![[Note]](../stylesheet/note.png) |
Note | |||||
|---|---|---|---|---|---|---|
|
DESCRIPTION
These functions convert lowercase letters to uppercase, and vice versa.
If c is a
lowercase letter, toupper()
returns its uppercase equivalent, if an uppercase
representation exists in the current locale. Otherwise, it
returns c. The
toupper_l() function performs
the same task, but uses the locale referred to by the locale
handle locale.
If c is an
uppercase letter, tolower()
returns its lowercase equivalent, if a lowercase
representation exists in the current locale. Otherwise, it
returns c. The
tolower_l() function performs
the same task, but uses the locale referred to by the locale
handle locale.
If c is neither an
unsigned char value nor
EOF, the behavior of these
functions is undefined.
The behavior of toupper_l()
and tolower_l() is undefined if
locale is the special
locale object LC_GLOBAL_LOCALE
(see duplocale(3)) or is not a
valid locale object handle.
RETURN VALUE
The value returned is that of the converted letter, or
c if the conversion
was not possible.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
|
|
Thread safety | MT-Safe |
CONFORMING TO
toupper(), tolower(): C89, C99, 4.3BSD, POSIX.1-2001,
POSIX.1-2008.
toupper_l(), tolower_l(): POSIX.1-2008.
NOTES
The details of what constitutes an uppercase or lowercase letter depend on the locale. For example, the default “C” locale does not know about umlauts, so no conversion is done for them.
In some non-English locales, there are lowercase letters with no corresponding uppercase equivalent; the German sharp s is one example.
COLOPHON
This page is part of release 4.07 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
Copyright (c) 1993 by Thomas Koenig (ig25rz.uni-karlsruhe.de) and Copyright 2014 Michael Kerrisk <mtk.manpagesgmail.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 (faithcs.unc.edu) Modified 2000-02-13 by Nicolás Lichtmaier <nickdebian.org> |