So, for example

my $inner;
unzip "my.zip" => \$inner;

# remove all whitespace
$inner =~ s/\s+//g;

print $inner;
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The code then makes use of the uncompressed data in this case to remove all whitespace, then print it.

$apples = 10;
$pears = 6;

take_one(\$apples);   # take one apple
take_one(\$pears);    # take one pear

print "I've still got $apples apples and $pears pears.\n";

sub take_one {
    my $ref = shift;  # a reference
    $$ref--           # access the value of the referenced scalar
}
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I've still got 9 apples and 5 pears.
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For more info, check out perlreftut and perlref.

It's easy for a programmer to detect if a value is a reference: just use ref: it'll return an empty string for a normal string, and "SCALAR" for a reference to a scalar.

It's a convention among module authors to use a reference to a scalar if you want to actually use the string value as data, instead of as a file name from which you'll read the contents; for example in the various HTML parsing modules.

I see. Usually for Methods I would simply read what it requires and what outputs it will give. In the case of Zip, I couldnt find any sources that says the code is valid (like unzip $file, \$inner, Name => '1.zip'; , it still looks wrong to me but it works). Thanks once again.