I have to warn you, that comparing to true or false is a very unperlish thing to do. 1 is considered as true, yes, but so is 2, 3.14, and "aardvark". In short: don't ever do 
  if($flag==true) { ...

[download]
because you'll get a false response for any case where $flag is a true value, but not the same as the value for your constant true.

In Perl, you should just be using 

  if($flag) { ...

[download]
if you want to test if it's true, and any of 
  if(!$flag) { ...

  if(not $flag) { ...

  unless($flag) { ...

[download]
to test for false.

p.s. An additional warning: All of undef, 0, "" and "0" are considered false in Perl. Perhaps that's too forgiving for you, and you explicitely want to distinguish between them. Use of defined, and of 

  $value eq ""

[download]
are typical idioms to deal with that. And no, you're not supposed to make a distinction between 0 and "0".

Thank you for your time.

In reply to Re: question about the Truth by bart
in thread question about the Truth by sH4ke

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.