in reply to A C-like brain in a Perl-like world

Of course TMTOWTDI (variation on tachyon's theme, really):

sub unique_merge {
   my ( %hash ) = map {$_ => 1 } @_ ;
   return keys %hash
}

my @array1 = qw(a b c d e) ;
my @array2 = qw(c d e f) ;
my @merged_array = unique_merge(@array1, @array2) ;

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Hashes may only have one key per value, so the task becomes how to get make a hash out of an array (or two). Using map I turn the arrays into key/value pairs (the value is not so important) and then ask for the keys back.

HTH

-Ducky

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Re (tilly) 2: A C-like brain in a Perl-like world
by tilly (Archbishop) on Sep 27, 2001 at 00:01 UTC
    Using keys in this way causes stringification of values. If your arrays have objects or references in them, this will bite. Also note that that 2 for 1 map was slow until Perl 5.6.1. The following is therefore how I do that: 
    sub unique_merge {
  my %seen;
  grep !$seen{$_}++, @_;
}

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    Side benefit? I don't lose the order of the incoming elements. :-) But, as with all hash approaches, my definition of "unique" is "stringifies the same". That is not always the appropriate definition to use.
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