How to get the value of a variable in child class from parent class

Question

This is the error I am getting:-

Fatal error: Cannot use 'Parent' as class name as it is reserved in C:\\xampp\\htdocs\\test\\home.php on line 3

Here is my code:

<?php
    class Parent{
      public $num1 = 3;
    }
    class Child extends Parent{
        public $sum = 2 + $this->num1;
    }
    $obj = new Child();
    echo $obj->sum;
    ?>

Answer 1

You can't use Parent as a class name and you can assign $sum an initial value using $sum = 2 + $this->num1; .

// renamed parent class
class ParentClass {
   public $num1 = 3;
}

// renamed child class
class ChildClass extends ParentClass {
    public $sum ;

    // a constructor is where you would do this type of math
    function __construct() {
        $this->sum = 2 + $this->num1;
    }
}

// create your child object
$obj = new ChildClass();
echo $obj->sum;

Answer 2

You have defined variable in the wrong way, The variable should be var $num = 3;

class Parent{
      var $num1 = 3;
    }
    class Child extends Parent{
        public function sum() { 
         return 2 + $this->num1;
    }
    }
    $obj = new Child();
    echo $obj->sum();