Regarding the issue of whether subclasses will automatically call the parent class constructor

Question

<?php

header("content-type:text/html;charset=utf-8");

class nn//This code is obvious. The class automatically calls the constructor of the parent class. . . .

{

public $name;

public function __construct()

{

echo 'I am in the nn class Constructor! <br>';

//$this->name=$iname;

}

}

class mm extends nn

{

}

$p=new mm;

?> ;