Accessing the $age variable using this->
<?php class Cat { var $age; function Cat($new_age){ $this->age = $new_age; } function Birthday( ){ $this->age++; } } $fluffy = new Cat(1); echo "Age is $fluffy->age <br />"; echo "Birthday<br/>"; $fluffy->Birthday( ); echo "Age is $fluffy->age <br />"; ?>