title: how to compare date string in Perl
body: <p>I have two  Perl string  variables containing date values.  I want to check whether str1 variable date value is 1 day before the str2 value.  How can i check it?  if it doesn't have 1 day before str2 then i need to print an error message. </p>
  
  <pre><code> $str1="20120704"
   $str2="20120705
  </code></pre>