Here are some basics about Perl hashes that can be helpful to be used when an you need to associate a label with some value such as for names and telephone numbers or account numbers with amounts owed.
Create a hash variable.
my %hashvar;
Create a hash reference
my $refhash = {};
Add a value to a hash variable.
$hashvar{'somekey'} = 'someval';
Add a value to a hash reference.
$hashref->{'somekey'} = 'someotherval';
Access a value in a hash.
print $hashvar{'somekey'};
Access a value in a hash reference.
print $hashref->{'somekey}';
Access all Keys in a hash variable.
foreach my $k (keys(%hashvar))
{
print $hashvar{$k};
}
Access all Keys in a hash reference.
foreach my $k (keys(%$hashref))
{
print $k . "n";
}
Access all Keys and values in a hash.
while (my ($key,$value) = each %hashvar)
{
print "Key: " . $key . " has value:" . $value . "n";
}
Access all Keys and values in a hash.
while (my ($key,$value) = each %$refhash)
{
print "Key: " . $key . " has value:" . $value . "n";
}
Assigning multiple values to a hash
%hasvar = ( 'test2' => 'myval', 'test3' => 'myval3' );
Note: This will clear the existing hash.
Delete a value from a hash
delete $hashvar{'key1'};
Delete a value from a hash reference.
delete $hashref->{'key1'};