=over

=item uc EXPR
X<uc> X<uppercase> X<toupper>

=item uc

Returns an uppercased version of EXPR.  If EXPR is omitted, uses
L<C<$_>|perlvar/$_>.

    my $str = uc("Perl is GREAT"); # "PERL IS GREAT"

This function behaves the same way under various pragmas, such as in a locale,
as L<C<lc>|/lc EXPR> does.

If you want titlecase mapping on initial letters see
L<C<ucfirst>|/ucfirst EXPR> instead.

B<Note:> This is the internal function implementing the
L<C<\U>|perlop/"Quote and Quote-like Operators"> escape in double-quoted
strings.

    my $str = "Perl is \Ugreat\E"; # "Perl is GREAT"

=back