NAME

       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 behaviour 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

       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  corresponding  uppercase  equivalent;
       the German sharp s is one example.

SEE ALSO

       isalpha(3), setlocale(3), locale(7)

GNU                                               April 4, 1993                                       TOUPPER(3)