PHP OOP: Issues with properties and extended class -

let's have php script:

<?php  class aaa {     protected $var = null;      public function performsomething()     {         $this->var = 'now have string, not more null value';         $bbb = new bbb();         $bbb->poweronyou();      } }   class bbb extends aaa {     public function poweronyou()     {         var_dump($this->var);         // dump "null" , not string     } }   $aaa = new aaa(); $aaa->performsomething(); 

how can note class "var_dump" everytime null, , not string.

of course need output string.

this sandbox link: http://sandbox.onlinephpfunctions.com/code/6cd253e1945e78f114749be55ffc5f88ab44dd42

thank you

note $var instance variable, not class variable. means, every instance of class has own copy of it.

you create instance of class aaa , set $aaa's copy of $var 'now have string, not more null value'. however, inside performsomething(), create new instance of class bbb, has own copy of $var. since did not set $bbb's $var, null when output it.

have @ code , try understand it; did not have opportunity test since @ work right now, should give desired output:

<?php  class aaa {     protected $var = null;      public function poweronyou()     {         var_dump($this->var);     } }   class bbb extends aaa {     public function performsomething()     {         $this->var = 'now have string, not more null value';         $this->poweronyou();     } }   $bbb = new bbb(); $bbb->performsomething();