Hi beginr,

I can see that this is your first post, Welcome to the Monastery! Make yourself at home., Please read Perl monks Faqs and do Super Search before posting.

@newarray = grep (!$unique{$_}++, @array);
print @newarray;
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There are some modules as well List::Unique, List::Uniq etc.

For example using that code:

my %seen;
my @distinct_elems = grep { !$seen{$_}++ } @array;
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or maybe

my %seen = map { $_ => 1 } @array;
my @distinct_elems = keys %seen;
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The first example even gives you the number of occurence of each element.

Cheers, Flo

Well, guess what? ...it is.

#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;
use Data::Dumper;
my @array = ( 1, 2, 3, 4, 5, 1, 2, 3, 99 );
my %seen = ();
my @unique_elements = ();
foreach my $element (@array)
{
    push (@unique_elements, $element) unless
        $seen{$element}++;
}

print Dumper @array;
print Dumper @unique_elements;
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While it's a fairly common idiom to produce, and the usual manner is to use a hash to filter uniques, it's less error-prone to simply use the common module, List::MoreUtils, with its uniq() method.

use strict;
use warnings;
use List::MoreUtils qw( uniq );
my @array = (1, 1, 3, 2, 8, 9, 4, 2, 3);
print uniq( @array ), "\n";
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Which.. guess what..

sub uniq (@) {
    my %h;
    map { $h{$_}++ == 0 ? $_ : () } @_;
}
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uses a hash!

Whilst in principal using a module is often a good thing, maybe it would be better if the OP understood what was going on under the hood first?

Just my not so humble opinion.

jdtoronto

my @a = ( 1..3, 2..3, 6, 8..9);
# Extract unique elements


print { @@{@a}=$,=' '; \*STDOUT}  keys(%@);
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my @a = ( 1..3, 2..3, 6, 8..9);
my $last_element = "";
my @sorted_aray = sort(@a);
foreach $i (@aorted_array){
  if ($last_element ne $i){
    print $i;
    $last_element = $i;
  }
}
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