• View
• Edit
• History
• Print

Hash

#############################

Question

How to use a hash?

Answer

Example 1

Creating and filling a hash.

my %hashTable = ();     # empty hash

$hashTable{'A'} = 'Aladar';
$hashTable{'B'} = 'Bela';
$hashTable{'C'} = 'Cecil';

Example 2

Printing key - value pairs.

while ( my ($key, $value) = each(%hashTable) ) {
   print "$key => $value\n";
}

A => Aladar
C => Cecil
B => Bela

Example 3

Check if a hash value is defined.

if (defined $hashTable{'B'}) {
   print "B is defined\n";
}
else {
   print "B is NOT defined\n";
}

if (defined $hashTable{'D'}) {
   print "D is defined\n";
}
else {
   print "D is NOT defined\n";
}

B is defined
D is NOT defined

More info

• http://www.cs.mcgill.ca/~abatko/computers/programming/perl/howto/hash/