​x
 
<!DOCTYPE html>
<html>
<body>
​
<?php
class Fruit {
  public $name;
  public $color;
  public function __construct($name, $color) {
    $this->name = $name;
    $this->color = $color; 
  }
  protected function intro() {
    echo "水果是 {$this->name}，颜色是 {$this->color}。"; 
  }
}
​
class Strawberry extends Fruit {
  public function message() {
    echo "我是水果还是浆果？ "; 
  }
}
​
// 尝试从类外部调用所有三个方法
$strawberry = new Strawberry("草莓", "红色");  // 允许。__construct() 是公共的
$strawberry->message(); // 允许。message() 是公共的
$strawberry->intro(); // 错误。intro() 是受保护的
?>
 
</body>
</html>