"Perl for Perl Newbies" - Part 2HashesHash-Related Functions

2.1. Hash-Related Functions

delete

delete can be used to remove a key or a set of keys out of a hash. For example:

$myhash{"hello"} = "world";
$myhash{"perl"} = "TMTOWTDI";
$myhash{"shlomi"} = "fish";

if (exists($myhash{"perl"}))
{
    print "The key perl exists!\n";
}
else
{
    print "The key perl does not exist!\n";
}

delete($myhash{"perl"});

if (exists($myhash{"perl"}))
{
    print "The key perl exists!\n";
}
else
{
    print "The key perl does not exist!\n";
}

The Comma Regarding Hashes

The comma can be used to combine two arrays into one larger one. Given the fact that a mini-hash with one key and one value can be specified using the $key => $value notation (which is essentially equivalent to $key, $value) a hash can be initialized in one statement.

Here's an example:

%hash1 = (
    "shlomi" => "fish",
    "orr" => "dunkelman",
    "guy" => "keren"
    );

%hash2 = (
    "george" => "washington",
    "jules" => "verne",
    "isaac" => "newton"
    );

%combined = (%hash1, %hash2);

foreach $key (keys(%combined))
{
    print $key, " = ", $combined{$key}, "\n";
}

If the two combined hashes contain several identical keys, then the values of the latter hash will win.


Written by Shlomi Fish