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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:
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:
print "Now there are \$basket{cherry}.\n";

print "Double Banana Bonus! \$basket{banana} bananas in the basket!\n";

# Add an element:

# 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:
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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