Tinkering with Perl

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Assignment of hashes

Hashes may be assigned one of two ways: one of which remembles a scalar, and the other of which is like the assignment of a list.

Recall the earlier example where John, Sue, and Mary have a dog, a cat, and a goldfish respectively. The easiest way, and the one you should probably use most of the time (until you've outgrown this book), is to say, "John's pet is a dog. Sue's pet is a cat. Mary's pet is a goldfish." In Perl, we write it this way:

$Pet{"John"} = "dog";
$Pet{"Sue"} = "cat";
$Pet{"Mary"} = "goldfish";

Remember that $Pet{"John"} should be read as "John's pet." This means that the whole statement should be read, "Let John's pet be a dog." Even though the computer statement looks rather funny, it really says something that is fairly close to English.

The second way makes a bunch of assignments at once — it is useful when you want to create a hash from scratch. Creating the same hash this way would look like this:

%Pet = ("John" => "dog",
	"Sue"  => "cat",
	"Mary" => "goldfish");

Now, did you notice that the statement was broken over a few lines? It's OK to split a statement over several lines and put spaces in to format it; indeed, it is good to do so. It makes the code more readable. This is called spacing.

Tinkering with Perl

Assignment of hashes

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