toupper, tolower - convert letter to upper or lower case
SYNOPSIS
#include <ctype.h>int toupper(int c); int tolower(int c);
DESCRIPTION
toupper()
converts the letter
c
to upper case, if possible.
tolower()
converts the letter
c
to lower case, if possible.
If
c
is not an
unsigned char
value, or
EOF,
the behavior of these functions
is undefined.
RETURN VALUE
The value returned is that of the converted letter, or
c
if the conversion was not possible.
CONFORMING TO
C89, C99, 4.3BSD.
BUGS
The details of what constitutes an uppercase or lowercase letter depend
on the current 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.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
