use strict;

my ($X, $Y);

modifyvars($X, $Y);
print "after: X=$X, Y=$Y\n";

sub modifyvars {
    $_[0] = 'foo';
    $_[1] = 'bar';

    my $rc = 0;
    $rc = 1 if $_[0] ne 'x';
    return 0;
}