PHP Tutorials - Herong's Tutorial Examples - v5.17, by Herong Yang
What Is in an Object Variable
This section describes what is in an object variable - An object variable actually contains the object identifier that points to where the object is stored.
What Is in an Object Variable? An object variable actually contains the object identifier that points to where the object is stored.
Don't confuse object variables with variable references. They are totally different concepts. If they are used together with objects, you should expect the following behaviors:
To help us understand the relations of objects, identifiers, variables and references, let's consider the following PHP code:
$a = new C(); $b = $a; $x = new C(); $y = &$x; $z = &$y; $o = $z;
After execution, we should have the following in memory:
Variable Variable Object List Contents List $a -------> Identifier #1 -------> Object #1 | $b -------> Identifier #1 --- $x -------> Identifier #2 -------> Object #2 | | $y --- | | | $z --- | | $o -------> Identifier #2 ---
As you can see from the above illustration, an object can be shared by two variables in two ways:
The picture provides a better illustration of the above code and the execution result in memory:
Table of Contents
Introduction and Installation of PHP
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
Interface with Operating System
►Introduction of Class and Object
What Is a Superclass and a Subclass
What Is an Overloaded Property
What Is Object Property Iteration
►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
Parsing and Managing HTML Documents
Configuring and Sending Out Emails
Managing PHP Engine and Modules on macOS