Your answer is here. Just look for the (second) listed type of variable, arrays.

Here is the bit you want to see (about arrays in scalar context).

You might be tempted to use $#array + 1 to tell you how many items there are in an array. Don't bother. As it happens, using @array where Perl expects to find a scalar value ("in scalar context") will give you the number of elements in the array: 1. if (@animals < 5) { ... }
Here is your program using those features. 
#!/usr/bin/perl
use strict;
use warnings;

# the program
my %hash = (
        'one' => [1],
        'two' => [2,2],
        'three' => [3,3,3],
);

print "$hash{one}[0]\n";
print "$hash{two}[0]\n";
print "$hash{three}[0]\n";

while (my ($key, $aref) = each %hash) {
    # dereference array_reference
    # (and the @$aref array is in scalar context)
    printf "key=%s size=%d\n", $key, @$aref;
}

[download]
Prints: 
1
2
3
key=three size=3
key=one size=1
key=two size=2

[download]

In reply to Re: length or array in a hash by Cristoforo
in thread length or array in a hash by ongaku

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.