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 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 possi-
       ble.

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.

SEE ALSO
       isalpha(3), setlocale(3), towlower(3), towupper(3), locale(7)

COLOPHON
       This  page  is  part of release 3.53 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/.



GNU                                         1993-04-04                                 TOUPPER(3)