hash size

[Galen]

Is there a method for directly retrieving the size of a hash, or must I use an array?

%somehash = ( key1 => "value1",
              key2 => "value2",
              key3 => "value3,
              key4 => "value4",
             );
@keys = keys %somehash;
$size = @keys;
print "This hash holds $size key-value pairs\n";

[davorg]

$size = keys %somehash;

Will work just fine.

--
<http://www.dave.org.uk>

"Perl makes the fun jobs fun
and the boring jobs bearable" - me

[arturo]

"size of a hash" isn't really well defined. You can get the number of keys, or the number of values pretty easily. (does a key w/o a defined value count? It might not for some purposes). You can cut down the keystrokes on your method with something like the following:

print "This hash holds ". scalar keys %somehash . " keys\n";

HTH

perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); 
+$rose = "smells sweet to degree $n";*other_name = *rose;print "$other
+_name\n"'

[larsen]

Another point from perldata. It could be useful for a certain definition of size :)...

If you evaluate a hash in a scalar context, it returns a value which is true if and only if the hash contains any key/value pairs. (If there are any key/value pairs, the value returned is a string consisting of the number of used buckets and the number of allocated buckets, separated by a slash. This is pretty much useful only to find out whether Perl's (compiled in) hashing algorithm is performing poorly on your data set. For example, you stick 10,000 things in a hash, but evaluating %HASH in scalar context reveals "1/16", which means only one out of sixteen buckets has been touched, and presumably contains all 10,000 of your items. This isn't supposed to happen.)

[zigster]

Not really AFAIC. You can shorten things sumwhat by calling keys in scalar context:

%somehash = ( key1 => "value1",
              key2 => "value2",
              key3 => "value3,
              key4 => "value4",
             );
$size = keys %somehash;
print "This hash holds $size key-value pairs\n";


--

Zigster