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Re^3: Replacing values in an array

by muba (Priest)
on Jan 27, 2013 at 05:17 UTC ( #1015561=note: print w/replies, xml ) Need Help??

in reply to Re^2: Replacing values in an array
in thread Replacing values in an array

You can consider a hash to be much like an array, except instead of numerical indexes to access individual elements, you use strings as keys.

# Define an array: my @basket = qw(apple banana cherry); # Get an element from the array: # (remember that indexes are 0-based) print "The second kind of fruit in the basket is $basket[1]\n"; # Change an element: $basket[1] = "date"; print "Now it is $basket[1]\n";

The above example shouldn't be unfamiliar. Now, instead of keeping a @basket that tells us what kinds of fruit we have in the basket, let's keep a %basket that can also tell us how much of that kind of fruit we have.

# Define the hash: my %basket = ( apple => 12, banana => 6, cherry => 32, # This final comma is optional, ); # but makes it easier to add more lines in the f +uture. # Get an element from the basket: print "There are $basket{cherry} cherries in the basket.\n"; # Modify elements: $basket{cherry}--; print "Now there are $basket{cherry}.\n"; $basket{banana} *= 2; print "Double Banana Bonus! $basket{banana} bananas in the basket!\n"; $basket{apple} = 10; # Add an element: $basket{date} = 16; # Get all keys in the hash: print "Fruits in my basket: ", join(", ", sort keys %basket), "\n"; # Using a variable as a key: for my $fruit (sort keys %basket) { print "You want a(n) $fruit? I have $basket{$fruit} in my basket.\ +n"; } # The 'each' function: while (my ($fruit, $amount) = each %basket) { print "There are $amount ${fruit}s in my basket.\n"; } # Getting rid of an element: delete $basket{apple}; print "Fruits in my basket: ", join(", ", sort keys %basket), "\n";

That pretty much covers the basics of hashes. Nothing to be afraid of, and quite a useful data type!

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