Constructor in Inheritance in OOP in PHP

When inheriting, you can override the parent's constructor. Let's look at an example. Suppose we have the following parent class:

php<?php
  class User {
    private $name;
    private $surn;
    
    public function __construct($name, $surn) {
      $this->name = $name;
      $this->surn = $surn;
    }
    
    public function getName() {
      return $this->name;
    }
    public function getSurn() {
      return $this->surn;
    }
  }
?>

Suppose the following class inherits from the parent class:

php<?php
  class Student extends User {
    
  }
?>

Suppose we want to extend the constructor in the child class by adding additional parameters to it:

php<?php
  class Student extends User {
    private $year;
    
    public function __construct($name, $surn, $year) {
      
    }
  }
?>

In this case, we must call the parent constructor via parent::__construct() on the first line:

php<?php
  class Student extends User {
    private $year;
    
    public function __construct($name, $surn, $year) {
      parent::__construct($name, $surn);
    }
  }
?>

The parent::__construct() command is essentially the parent's constructor. Therefore, let's pass the required parameters into it:

php<?php
  class Student extends User {
    private $year;
    
    public function __construct($name, $surn, $year) {
      parent::__construct($name, $surn);
    }
  }
?>

Now, in the child class, let's record the year of study in the child's own property:

php<?php
  class Student extends User {
    private $year;
    
    public function __construct($name, $surn, $year) {
      parent::__construct($name, $surn);
      $this->year = $year;
    }
  }
?>

Let's make a getter for the year of study:

php<?php
  class Student extends User {
    private $year;
    
    public function __construct($name, $surn, $year) {
      parent::__construct($name, $surn);
      $this->year = $year;
    }
    
    public function getYear() {
      return $this->year;
    }
  }
?>