my @arr = (1,2,2,3,4,4,5); 
output should be @arr = (1,2,3,4,5);

#!/usr/bin/perl 
 
use strict; 
 
my @arr = (1,2,2,3,4,4,5); 
my %seen; 
 
map { $seen{$_}++ } @arr; 
print sort keys %seen;

#!/usr/bin/perl 
 
use strict; 
 
my @arr = (1,2,2,3,4,4,5); 
my @uniq; 
 
for my $i (@arr) { 
    push( @uniq, $i ) if ( ! grep { /\b$i\b/ } @uniq ); 
} 
 
print join ',', sort @uniq;

use strict; 
use warnings; 
 
 
use List::MoreUtils qw(uniq); 
my @unique = uniq( 1, 2, 3, 4, 4, 5, 6, 5, 7 ); 
print "@unique\n";

1,2,3,4,5,6,7