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



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.

       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 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(a), setlocale(e), locale(e)



GNU                         1993-04-04                 TOUPPER(R)