23、面向对象例子-类继承

class TestParent
{

public $param1 = ‘param1’;

protected $param2 = ‘param2’;

private $param3 = ‘param3’;

public function func4()
{
echo ‘I am func4’,PHP_EOL;
}
}

class TestChild extends TestParent
{

public function func1()
{
echo $this->param1,PHP_EOL;
}

public function func2()
{
echo $this->param2,PHP_EOL;
}

public function func3()
{
echo $this->param3,PHP_EOL;
}

public function func4()
{
echo ‘child->I am func4’,PHP_EOL;
parent::func4();
}
}

// 测试方法
$tc = new TestChild();
$tc->func1();
$tc->func2();
$tc->func3();
$tc->func4();

• public(公开): 所有环境都能够访问

• protected(受保护): 如在父类进行修饰，则只能在子类内部进行访问

• private(私有): 只能在本类内部访问