<?
  class Animal
  {
     var $gender;
     var $age;
     function Animal($a_age,$a_gender='male')
     {
        $this->gender=$a_gender;
        if ($a_age>0)
           $this->age=$a_age;
        $age=0;
     }
     function PrintDetails($bold=true)
     {
        if ($bold)
           echo "<B>".$this->gender."</B> of age <B>".$this->age."</B>.";
        else
           echo $this->gender." of age ".$this->age.".";
     }
  }
  
  class Dog extends Animal
  {
     var $name;
     function Dog($age,$name='',$gender='female')
     {
        parent::Animal($age,$gender);
        $this->name=$name;
     }
     function PrintDetails()
     {
        echo $this->name." is a dog. It is a ";
        parent::PrintDetails(false);
     }
  }
?>

<?
  $animal1=new Animal(4);
  $animal2=new Animal();
  $dog1=new Dog(2,'Lady');
  $dog2=new Dog(4,'Rockey',"male");
?>

<?
  $doggie=new Dog(3,"Roller","male");
  $doggie->age++;
  $doggie->PrintDetails();
?>

<?
  Animal::PrintDetails();
?>