Introduction of Class and Object
This chapter provides tutorial notes and example codes on class and object. Topics include introduction of class and object; static variables and methods; superclass and subclass; abstract class and method; interface and trait; overloaded properties and methods; object cloning and serialization; references or aliases of object variables.
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
- A class is a user defined datatype which is associated with a predefined set of properties and operations (also called methods).
- An object is a data entity that is created as an instance of a class.
- A static variables and methods are declared at the class level and can be accessed without any object of the class.
- A superclass and a subclass is a pair of classes that the second class extends from the first class to inherit all properties and operations from the fist class.
- An abstract class is considered to be not fully completed and is required to be extended into subclasses to complete the definition.
- An abstract method only has its calling signature declared with no implementation code and is required to be implemented in subclasses.
- An interface is a like a "half" abstract class that only declares some abstract methods and has no properties.
Any class who wants to implement an interface must implement its abstract methods.
- A trait is a pseudo class that defines a set of properties and operations.
Any class can use a trait to inherit its properties and operations.
- An overloaded property is indirectly provided through implementations of __set(), __get(), __isset(), and __unset() methods.
- An overloaded method is indirectly provided through the implementation of the __call() or the __callStatic() method.
- Object cloning can be done easily by using the "clone" operator.
- Object serialization and unserialization can be easily done calling serialize() and unserialize() functions.
- An object variable actually stores the identifier that points to the object.
- A variable alias can be created by taking the reference of of the variable.
- Object variables can be passed as function arguments using pass-by-value mode or pass-by-reference mode.
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
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
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