use warnings;
use strict;

mysub('duff');   

sub mysub() {
        print "mysub\n"
}

##</code><code>##

main::mysub() called too early to check prototype

##</code><code>##

use warnings;
use strict;

sub mysub();    # mysub declaration

mysub('duff');

sub mysub() {
        print "mysub\n"
}

##</code><code>##

Too many arguments for main::mysub