How to create the class constructor in PHP

Overview

In OOP, when a constructor is declared, it initializes the properties of an object.

The __construct function

In PHP, we have the __construct function for such purposes.

Note: We use the double underscore __ before construct.

Once we have the __construct() function in a class, the subsequent object of that class will initiate the variables and the functions inside it. Therefore, we don’t have to manually create/initialize them.

Code

For instance, in the provided example, we don't have to call the specific functions, set_brand() and set_name() to initialize the brand and name variables. This is because it's been done by the __construct() function that saves up our code space and reduces the manual efforts/steps we have to perform for such purposes.

<?php
class Car {
  public $brand;
  public $name;
  function __construct($brand, $name) {
    $this->brand = $brand;
    $this->name = $name;
  }
  function get_brand() {
    return $this->brand;
  }
  function get_name() {
    return $this->name;
  }
}
$car1 = new Car("Honda", "Civic");
echo $car1->get_brand();
echo " ";
echo $car1->get_name();
?>

Explanation

  • Lines 1-18: We create a class named Car with a brand and a name. Then, we create the __construct function and pass the brand and name as its parameters. This function initializes the brand and name with the input that the user provides when it creates a class object. Furthermore, we create a get_brand() and get_name() function to return the brand and name that is assigned to the class object.
  • Lines 20-23: We create a Car object car1 and pass it the brand and name in the braces. After this, we simply print the brand and name through the get functions.

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