You do it using a hash like this - it is rather brief :-) but that's perl for you:

sub merge {
    my %hash;
    $hash{$_}++ for @_;
  return keys %hash;
}

sub intersection {
    my %hash;
    $hash{$_}++ for @_;
  return grep { $hash{$_} > 1 } keys %hash
}

sub lookup {
    $value = shift;
    for (@_) {
        return 1 if $value eq $_;
    }
  return 0;
}
    

@ary1 = qw( a b c d e f g );
@ary2 = qw( e f g h i j k );
print merge ( @ary1, @ary2), "\n";
print intersection ( @ary1, @ary2 ), "\n";
for ( qw( j a p h ) ) {
    print lookup( $_, @ary2) ? "$_ Found\n" : "$_ Not found\n";
}
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There is a thing called the Perl FAQ which is nine documents covering all the common stuff you will want to do like merge arrays, find intersections.....

By the way it will be a good idea to lose the TRUE FALSE habit. In perl everything is true except for:

• 0 (including the string equvalents "0" which evaluates to zero)
• '' - the null string
• undef - an undefined value
• () - an empty list/array

This is really handy as it lets you do stuff like print @array if @array which will only print @array if it contains elements and is thus true or &some_func if $flag which will only call the sub if $flag is true. This also means that unless you have defined a sub sub FALSE { 0 } that when you think you return FALSE you don't.

sub oops {
   return FALSE;
}
print "Oops 'FALSE' is true in Perl" if &oops;
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Update

CheeseLord points out a error in my understanding. Thanks!

cheers

tachyon

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