<?php
class validateForm {
	
  public $_define_string;
  public $_define_errors;
  
  public function isEmpty($_define_string) {
	  if(empty($_define_string)) {
		$this->_define_errors = "This string is pretty much empty...";
		return 0;  
	  } else {
		return 1;
	  }
  }

}

$_string_validate = '';

$validateForm = new validateForm();
$validateForm->isEmpty($_string_validate);
if(!empty($validateForm->_define_errors)) {
	echo $validateForm->_define_errors;
}
?>