PHP get_parent_class

 <?php
 class D
 {
 }

 class A extends D
 {

 }

 class B extends  A
 {
 }

 function getAncestor($class){
     $parent = get_parent_class($class);
     if($parent){
         echo $parent ."\n";
         getAncestor($parent);
     }
 }

 getAncestor('B');