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TOUPPER(3) Linux Programmer's Manual TOUPPER(3)
NAME
toupper, tolower - convert letter to upper or lower case
SYNOPSIS
#include<ctype.h>
inttoupper(int c);
inttolower(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 behaviour of these
functions is undefined.
RETURNVALUE
The value returned is that of the converted letter, or c if the conver-
sion was not possible.
CONFORMINGTO
ANSI C, BSD 4.3
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 cor-
responding uppercase equivalent; the German sharp s is one example.
SEEALSO
isalpha(3), setlocale(3), locale(7)
GNU 1993-04-04 TOUPPER(3)
Take our 
