PHP | Type Casting and Conversion of an Object to an Object of other class

Last Updated : 09 Jan, 2019

Given a PHP class object and the task is to convert or cast this object into object of another class. Approach 1: Objects which are instances of a standard pre-defined class can be converted into object of another standard class. Example:

php

<?php // PHP program to show  // standard type casting $a = 1; var_dump($a); // int to float $a = (float) $a; var_dump($a); // float to double $a = (double) $a; var_dump($a); // double to real $a = (real) $a; var_dump($a); // real to int $a = (int) $a; var_dump($a); // int to integer $a = (integer) $a; var_dump($a); // integer to bool $a = (bool) $a; var_dump($a); // bool to boolean $a = (boolean) $a; var_dump($a); // boolean to string $a = (string) $a; var_dump($a); // string to array $a = (array) $a; var_dump($a); // array to object $a = (object) $a; var_dump($a); // object to unset/NULL $a = (unset) $a; var_dump($a); ?>

Output:

 int(1) float(1) float(1) float(1) int(1) int(1) bool(true) bool(true) string(1) "1" array(1) { [0]=> string(1) "1" } object(stdClass)#1 (1) { [0]=> string(1) "1" } NULL

Approach 2: Create a constructor for final class and add a foreach loop for assignment of all properties of initial class to instance of final class. Example:

php

<?php // PHP program to convert an class object // to object of another class // Original class class Geeks1 { var $a = 'geeksforgeeks'; function print_geeksforgeeks() { print('geeksforgeeks'); } } // Final class class Geeks2 { // Constructor function of class Geeks2 public function __construct($object) { // Initializing class properties foreach($object as $property => $value) { $this->$property = $value; } } } // Initializing an object of class Geeks1 $object1 = new Geeks1(); // Printing original object of class Geeks1 print_r($object1); // Initializing an object of class Geeks2 // using an object of class Geeks1 $object1 = new Geeks2($object1); // Printing object of class Geeks2 print_r($object1); ?>

Output:

 Geeks1 Object ( [a] => geeksforgeeks ) Geeks2 Object ( [a] => geeksforgeeks )

Approach 3: Write a function to convert object of the initial class into serialized data using serialize() method. Unserialize this serialized data into instance of the final class using unserialize() method. Note: Member functions cannot be transferred using this approach. This approach can only be used if initial class contains only variables as members. Example:

php

<?php // PHP program to convert an class object  // to object of another class // Original class class Geeks1 { var $a = 'geeksforgeeks'; function print_geeksforgeeks() { print('geeksforgeeks'); } } // Final class class Geeks2 { /* Empty abstract class */ } // Function to convert class of given object function convertObjectClass($object, $final_class) { return unserialize(sprintf( 'O:%d:"%s"%s', strlen($final_class), $final_class, strstr(strstr(serialize($object), '"'), ':') )); } // Initializing an object of class Geeks2 $object1 = new Geeks1(); // Printing original object of class Geeks1 print_r($object1); // Converting an object of class Geeks1 // into an object of class Geeks2 $object1 = convertObjectClass($object1, 'Geeks2'); // Printing object of class Geeks2 print_r($object1); ?>

Output:

 Geeks1 Object ( [a] => geeksforgeeks ) Geeks2 Object ( [a] => geeksforgeeks )

Note: In general, PHP doesn't allow type casting of user defined classes, while conversion/casting can be achieved indirectly by approaches presented above.

PHP | Type Casting and Conversion of an Object to an Object of other class

Harshit Saini