Associative Arrays (Hashes)

You're wasting perl if you don't use associative arrays. Associative arrays, sometimes called "hashes", are arrays that are indexed not on ordered integers, but on arbitrary string values. Typically, elements of an associative array are refered to as "key" and "value" pairs - the "key" is used to find the element of the array that has the "value". Basic operators are:

% (percent sign): Refers to the entire array
{ } (braces): Used to denote the key
$: When used with { }, this is the value of the array element indexed on the key.

 
	$principal{"clarinet"} = "Susan Bartlett"; 
	$principal{"basson"} = "Andrew Vandesteeg"; 
	$principal{"flute"} = "Heidi Lawson"; 
	$principal{"oboe"} = "Jeanine Hassel"; 
	@woodwinds = keys(%principal); 
	@woodwindPrincipals = values(%principal);

Some Associative Array functions
keys(%ARRAY)	Return a list of all the keys in %ARRAY. The list is "unordered" - it depends on the hash function used internally.
values(%ARRAY)	Return a list of all the values in %ARRAY
each(%ARRAY)	Each time this is called on an %ARRAY, it will return a 2 element list consisting of the next key/value pair in the array.
delete($ARRAY{KEY})	remove the pair associated with KEY from ARRAY.

The National Center for Supercomputing Applications
University of Illinois at Urbana-Champaign

[email protected]

Associative Arrays (Hashes)

Last modified: June 19, 1997