filter_var function in php

<?php

      // The filter_var() function Returns the filtered data TRUE on success or FALSE on failure.
     $emailid='test@test.com';
        if(!filter_var($emailid, FILTER_VALIDATE_EMAIL))
        {
           echo("E-mail ID is Invalid");
        }
       else
        {
             echo("E-mail ID is valid ");
       }
?>