extends

A.php

 

<?php
 class A{
  function example()
  {
   echo "I am A::example() and provide basic funcionality.<br/>";
  }
 }
?>

 

B.php

 

<?php
 require_once('A.php');
 class B extends A{
  function example(){
   echo "I am B:example() and provide additional functionality.<br/>";
   parent::example();
  }
 }
 $b=new B();
 $b->example();
?>

 

输出：

I am B:example() and provide additional functionality.
I am A::example() and provide basic funcionality.