//自己调自己就是回调 实现了一个垒加2垒减2的效果
class digui{
public function index($number){
if($number>0) {
echo $number," ";
$this->index($number-2); //自己调自己就是回调
}
}
public function unindex($number1){
if($number1<=10){
echo $number1," ";
$this->unindex($number1+2);
}
}