=over

=item uc EXPR

=item uc

Returns an uppercased version of EXPR.  This is the internal function
implementing the C<\U> escape in double-quoted strings.  Respects
current LC_CTYPE locale if C<use locale> in force.  See L<perllocale>
and L<perlunicode> for more details about locale and Unicode support.
It does not attempt to do titlecase mapping on initial letters.  See
C<ucfirst> for that.

If EXPR is omitted, uses C<$_>.

=back