Manpage of TOUPPER

TOUPPER

Section: Linux Programmer's Manual (3)
Updated: 2016-10-08
Index
 

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);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

toupper_l(), tolower_l():

Since glibc 2.10:
_XOPEN_SOURCE >= 700
Before glibc 2.10:
_GNU_SOURCE
 

DESCRIPTION

These functions convert lowercase letters to uppercase, and vice versa.

If cis 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 cis 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 cis neither an unsigned charvalue nor EOF, the behavior of these functions is undefined.

The behavior of toupper_l() and tolower_l() is undefined if localeis 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 cif the conversion was not possible.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
toupper(), tolower(),
toupper_l(), tolower_l()
Thread safetyMT-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 Clocale 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.  

SEE ALSO

isalpha(3), newlocale(3), setlocale(3), towlower(3), towupper(3), uselocale(3), locale(7)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ATTRIBUTES
CONFORMING TO
NOTES
SEE ALSO

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