Why a protected variable of parent class come empty?

Question

I got a protected variable in Father class, the content of this variable will change in Father class but I need to use this variable in sub classes, i.

Answer 1

You have to invoke the parent constructor.

class Father {
   protected $body;
   function __construct(){
       $this->body = 'test';
   }
}

class Child extends Father {
   function __construct(){
       parent::__construct();
       echo $this->body;
   }
}

$c = new Father();
$d = new Child();

Reference: http://php.net/manual/en/language.oop5.decon.php

Answer 2

This is because you're overriding the constructor function. You must call the parent's constructor as well. More info

class Child extends Father {
    function __construct() {
        parent::__construct();

        echo $this->body;
    }
}