Hi monks, I have learned OOperl These day, and now had a small question. Below is a sentence chapter 10 package of Programming Perl Third Edition:
You can refer to identifiers5 in other packages by prefixing ("qualifying") the identifier with the package name and a double colon: $Package::Variable.

So,I have tried this: 
#!/usr/bin/perl
use warnings;
use strict;
use File::Find;
print $File::Find::Version,"\n";

__OUTPUT__
Name "File::Find::Version" used only once: possible typo at test.pl li
+ne 5.
Use of uninitialized value in print at test.pl line 5.

[download]
What does the error messages mean? And how do I use package variable?
Thanks in advance!

I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

In reply to Package Variable by xiaoyafeng

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.