Re: Array comparison using perl

...and not using any modules:

#!/usr/bin/env perl
#

use strict;
use warnings;


my @a1 = (1, 2, 3, 4, 5, 6, 7, 8, 9);
my @a2 = (1, 4, 5, 9 ,7);

print  "\@a1 is (".(join ",", @a1).")\n";
print  "\@a2 is (".(join ",", @a2).")\n";

my ($e1, $f);
my @a3;

for $e1 (@a1) {
    $f = 0;
    for (@a2) {
        if ($e1 eq $_) { $f++; }
    }
    unless ($f) { push @a3, $e1 }
}

print  "\@a3 is (".(join ",", @a3).")\n";
[download]

Comment on Re: Array comparison using perl Download Code

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Re^2: Array comparison using perl by GrandFather (Saint) on Dec 21, 2010 at 20:18 UTC
and what happens when the number of elements increases? This code is O(n²) which doesn't scale at all well. Better is something like: `my %hits; ++$hits{$_} for @a1; my @matched = grep {exists $hits{$_}} @a2;` [download] True laziness is hard work	[reply] [d/l]
Re^2: Array comparison using perl by ajguitarmaniac (Sexton) on Dec 21, 2010 at 14:54 UTC
Right on fisher! Thanks!	[reply]