Define('VARCHECK_FROM_POST', 0x02, True);
Define('VARCHECK_FROM_GET',  0x01, True);
Define('VARCHECK_MISSING',   0x00, True);

class VarCheckNothingFoundException extends Exception
{
  public function __construct()
  {
    parent::__construct('There where non of the specified Variables passed by the user.', 0x01);
  }
}
 
function VarCheck()
{
  global $HTTP_POST_VARS;
  global $HTTP_GET_VARS;

  $used = Array(
    'submit',
    'preview',
    'delete',
    'poll_delete',
    'poll_add',
    'poll_edit',
    'mode'
  ); 
  
  $aliases = Array(
    'post',
    'preview',
    'delete',
    'poll_delete',
    'add_poll_option',
    'edit_poll_option',
    'mode'
  );
  
  $locate = Array(); 
  
  $numParams = Count($params);

  $numMissing = 0x00;
  
  For($iter=0x00; $iter<$numParams; $iter=0x01+$iter)
  {
    $search = $used[$iter]; 
  
    If( IsSet($HTTP_POST_VARS[$search]) )
    {
      $locate[$iter] = VARCHECK_FROM_POST;
    }
    ElseIf( IsSet($HTTP_GET_VARS[$search]) )
    {
      $locate[$iter] = VARCHECK_FROM_GET;
    }
    Else
    {
      $locate[$iter] = VARCHECK_MISSING;
    }
  
    Switch($locate[$iter])
    {
      Case VARCHECK_MISSING:
        $buffer = Null;
        Break;
      Case VARCHECK_FROM_GET:
        $buffer = $HTTP_GET_VARS[$search];
        Break;
      Case VARCHECK_FROM_POST:
        $buffer = $HTTP_POST_VARS[$search];
    }
  
    If( $buffer !== Null )
    {
      If( (bool) Get_Magic_Quotes_Gpc() == True )
      {
        $buffer = StripSlashes($buffer);
      }
  
      $buffer = HTMLSpecialChars($buffer);
  
      $alias = $aliases[$iter];
      
      $code = "\$".$alias." = \$buffer;";
      Eval($code);
    }

    if($locate[$iter] === VARCHECK_MISSING)
    {
      $numMissing = 0x01+$numMissing;
    }
  
    UnSet($search);
    UnSet($buffer);
    UnSet($alias);
    UnSet($code);

    if($numMissing == $numParams Or $numMissing > $numParams)
    {
      break;
    }
  }
  
  UnSet($used);
  UnSet($aliases);
  UnSet($locate);
  UnSet($iter);

  if($numMissing == $numParams Or $numMissing > $numParams)
  {
    UnSet($numParams);
    UnSet($numMissing);
    
    throw new VarCheckNothingFoundException();
  }

  UnSet($numParams);
  UnSet($numMissing);

  return True;
}

Try {
  VarCheck();
} Catch(VarCheckNothingFoundException $nothingFoundException) {
  if( is_callable('gettext') )
  {
    $message = gettext($nothingFoundException->getMessage());
  }
  else
  {
    $message = $nothingFoundException->getMessage();
  }

  echo("<b>Error:</b> ");
  echo($message);
  echo("<br />");

  UnSet($message);
}