for ( my $i = 0; $i < @array; $i++ ) {
 ...
}

##</code><code>##

my @array = qw/ zero one two three four /;
for ( my $i = 0; $i < $#array; $i++ ) {
    print $array[$i],$/;
}

##</code><code>##

sub foo {
    my $arg = shift;
    foreach my $data ( @data ) {
        $bar[ $data ] += $arg;
    }
}