PHP Tutorials - Herong's Tutorial Examples - v5.17, by Herong Yang
What Is an Abstract Class
This section describes what is an abstract class - a class whose definition is considered to be not fully completed and is required to be extended into subclasses to complete the definition. No objects are allowed to be created from an abstract class directly.
What Is an Abstract Class? An abstract class is a class whose definition is considered to be not fully completed and is required to be extended into subclasses to complete the definition. No objects are allowed to be created from an abstract class directly.
In PHP, an abstract class is declared with the keyword "abstract". For example, the following tutorial example provides an abstract class MyShape which is extended by subclass MyCircle.
<?php
/* MyCircle.php
#- Copyright 2015 (c) HerongYang.com. All Rights Reserved.
*/
abstract class MyShape {
public $x;
public $y;
public $type;
public function __construct($x,$y,$t) {
$this->x = $x;
$this->y = $y;
$this->type = $t;
}
public function showType() {
echo " Type: " . $this->type ."\n";
}
public function showCenter() {
echo " Center: " . $this->x .", " . $this->y ."\n";
}
}
class MyCircle extends MyShape {
public $radius;
public function __construct($x,$y,$r) {
parent::__construct($x,$y,"Circle");
$this->radius = $r;
}
public function showArea() {
echo " Area: " . 3.1459*$this->radius**2 ."\n";
}
}
$object = new MyCircle(1.0,2.0,0.5);
echo "MyCircle object: \n";
$object->showType();
$object->showCenter();
$object->showArea();
?>
If you run the above tutorial example, you will get something like this:
herong> \php\php MyCircle.php MyCircle object: Type: Circle Center: 1, 2 Area: 0.786475
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
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