In your example, '>' has a higher precendence than '?:', as documented in perlop. You don't technically need the brackets in this case, but there are examples of where they are vitally important:
print $lines = $some_value? 'true' : 'false';
In this case, since '=' has a lower precendence, what actually gets evaluated is:
print $lines = ($some_value? 'true' : 'false');
This means $lines gets assigned a value of either 'true' or 'false'.
print ($lines = $some_value)? 'true' : 'false';
This actually assigns the proper value to $lines and prints accordingly.

For the sake of clarity, sometimes it's a good idea to just put the brackets in there anyway. Some editors allow you to bounce between bracket pairs, which can help when navigating complex conditions.

Update:
As Anarion is quick to point out, that last example is actually defective. It should be:
print (($lines = $some_value)? 'true' : 'false');
I think it was being parsed as something like:
(print $lines = $some_value)? 'true' : 'false';

In reply to Re: What difference do the brackets make? by tadman
in thread What difference do the brackets make? by kiat

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.