1. Perl Variables: Hash
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2. Hash (Associative Array)
Syntax
key and value pair
%hash = (key1, value1, key2, value2, ….);
Hash Elements
$hash{keyN} = valueN;
Assigning values
intialization
%hash = (element list);
%hash
%hash = (key1=>value1, key2=>value2, …);
assigning values to individual hash element
$hash{“key1”} = “value1”;
Hash elements are stored in a random order
 Example script
Web Programming

3. Hash Functions @keys = keys (%hash); @values = values (%hash);
return an array of hash keys
@values = values (%hash);
return an array of hash values
(key,value) = each (%hash);
return a key-value pair sequentially
delete ($hash{key});
deletes a hash element
exists ($hash{key})
returns true if key exists in %hash
 Example script
Web Programming

4. Printing Hash print %hash; print join (“:”,%hash);
hash is collapsed into an array and then printed
i.e.
print join (“:”,%hash);
hash collapsed into array is joined and printed
i.e. print join
while (($key, $value) = each %hash) { print “$key=$value\n”; }
foreach $key (sort keys %hash) { print “$key=$hash{$key}\n”; }
 Example script
Web Programming

5. Hash Examples
Word Count open(IN,$file) || die “can’t open close IN; foreach { @words= split(/ +/,$line); foreach { $wdcnt{$wd}++; } }  Example script
Web Programming