Just another point, passing the hashes as references means that at the other end you just have a "pointer" to the position in memory that the hash starts at. The data itself is not "copied" so you don't double the memory requirements. It also means that if you change any of the data inside the hash, it is the original that is modified. Consider the following code... 
#!perl -w
use strict;

my %hash = ( a => 1,
             b => 2,
             c => 3 );

sub change {
    my $hash = shift;
    $hash->{c} = 4;
}

change( \%hash );

for my $key (sort keys %hash) {
    print "$key : $hash{$key}\n";
}

__END__
Output looks like:
a : 1
b : 2
c : 4

[download]
The original was modified and without the hash being returned by the sub.

Hope this helps

"Argument is futile - you will be ignorralated!"

In reply to Re: why a by larryk
in thread why is a "\" needed before a hash in my subroutine call? by slok

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