TOUPPER(3)          Linux Programmer's Manual          TOUPPER(3)

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 possi-
       ble.

       tolower() converts the letter c to lower case,  if  possi-
       ble.

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 con-
       version 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                         1