What Is Object Cloning

This section describes what is object cloning - An easy way of creating a new object and copying all properties from an old object. PHP also allows you to implement __clone() method to modify properties of the newly created object.

What Is Object Cloning? Object cloning is an easy way of creating a new object and copying all properties from an old object. PHP also allows you to implement __clone() method to modify properties of the newly created object.

PHP uses the "clone" operator to clone an object and applies the following rules:

For example, the following tutorial example provides class "MyCarQuote" that shows how to use "__clone" method to alter the behavior of "clone" operation (The quote will go up by $400.00 each time you clone the object).

<?php 
/* MyCarQuote.php
#- Copyright (c) 2015-2019, HerongYang.com, All Rights Reserved.
*/

class MyCarQuote {
   public $maker = "BMW";
   public $model = "i8";
   public $year = "2015";
   public $color = "Silver";
   public $engine = "1.5L 3-cylinder";
   public $horsepower = "357 HP";
   private $quote = 123400.0;
   private $cost = 120000.0;
   public function __clone() {
      $this->quote += 400.00;
   }
   public function getQuote() {
      return $this->quote;
   }
}

   $car1 = new MyCarQuote();
   echo "First car specs: \n";
   foreach($car1 as $key => $value) {
      echo "   $key: $value\n";
   }
   $q = $car1->getQuote();
   echo "   -- quote: \$".intval($q/1000).",".($q%1000).".00\n";

   $car2 = clone $car1;
   echo "Second car specs: \n";
   foreach($car2 as $key => $value) {
      echo "   $key: $value\n";
   }
   $q = $car2->getQuote();
   echo "   -- quote: \$".intval($q/1000).",".($q%1000).".00\n";
?>

If you run the above tutorial example, you will get something like this:

C:\herong> \php\php MyCarQuote.php

First car specs:
   maker: BMW
   model: i8
   year: 2015
   color: Silver
   engine: 1.5L 3-cylinder
   horsepower: 357 HP
   -- quote: $123,400.00
Second car specs:
   maker: BMW
   model: i8
   year: 2015
   color: Silver
   engine: 1.5L 3-cylinder
   horsepower: 357 HP
   -- quote: $123,800.00

Last update: 2019.

Table of Contents

 About This Book

 Introduction and Installation of PHP 7.3

 PHP Script File Syntax

 PHP Data Types and Data Literals

 Variables, References, and Constants

 Expressions, Operations and Type Conversions

 Conditional Statements - "if" and "switch"

 Loop Statements - "while", "for", and "do ... while"

 Function Declaration, Arguments, and Return Values

 Arrays - Ordered Maps

Introduction of Class and Object

 What Is a Class

 What Is an Object

 What Is a Constructor

 What Is a Static Method

 What Is a Static Variable

 What Is a Superclass and a Subclass

 What Is an Abstract Class

 What Is an Abstract Method

 What Is an Interface

 What Is a Trait

 What Is an Overloaded Property

 What Is an Overloaded Method

 What Is Object Property Iteration

What Is Object Cloning

 What Is Object Serialization

 What Is in an Object Variable

 Updating Variables Who Share an Object

 Passing Objects as Function Arguments

 Integrating PHP with Apache Web Server

 Retrieving Information from HTTP Requests

 Creating and Managing Sessions in PHP Scripts

 Sending and Receiving Cookies in PHP Scripts

 Controlling HTTP Response Header Lines in PHP Scripts

 MySQL Server Connection and Access Functions

 Functions to Manage Directories, Files and Images

 SOAP Extension Function and Calling Web Services

 SOAP Server Functions and Examples

 Localization Overview of Web Applications

 Using Non-ASCII Characters in HTML Documents

 Using Non-ASCII Characters as PHP Script String Literals

 Receiving Non-ASCII Characters from Input Forms

 "mbstring" Extension and Non-ASCII Encoding Management

 Managing Non-ASCII Character Strings with MySQL Servers

 Configuring and Sending out Emails

 Outdated Tutorials

 References

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