Learn more about classes in php

The daily environment is composed of countless entities: plants, people, transportation, food... there are so many that it would take hours just to list them. Each entity is defined by a set of properties and behaviors

For example, a vehicle can be defined with properties such as color, number of tires, manufacturer, model, and capacity, and can be defined with stop, go, turn, and honk. Flute and other behaviors. In OOP terminology, a specific definition of the properties and behavior of an entity is called a class.
Definition and Creation of Classes
A class is a collection of objects with the same properties and services. It provides a unified abstract description for all objects belonging to this class, which includes two main parts: properties and methods. In object-orientedprogramming language, a class is an independent program unit. It should have a class name and include two main parts: attribute description and method description. Classes are used to represent the actual things to be processed in the application. For example, if you were creating an application to manage a public library, you might include classes to represent books, magazines, staff, special events, patrons, and other things that need to be managed. Each entity contains a set of properties and behaviors, called fields and methods in OOP, which define the entity. The general class creation syntax in PHP is as follows:

class Class_Name 
{ 
// 字段声明 
// 方法声明 
}

Create a class:

class Employee 
{ 
private $name; 
private $title; 
protected $wage; 
protected function clockIn() { 
echo "Member $this->name clocked in at ".date("h:i:s"); 
} 
protected function clockOut() { 
echo "Member $this->name clocked out at ".date("h:i:s"); 
} 
}

This class is called Employee and defines 3 fields: name, title and wage, and also defines two Methods: clockIn (check in) and clockOut (check out).

Application of classes
A class that defines attributes and methods is a complete class, and a complete processing logic can be included in a class. Use the new keyword to instantiate an object in order to apply logic within the class. Multiple objects can be instantiated simultaneously.

Instantiation of class:

Copy code

The code is as follows:

object = new class_name();

After instantiating an object, Use the ->

operator

to access the member properties and methods of the object. For example:

object->var_name; 
object->function_name;

If you want to access the properties or methods of members in the defined class, you can use the pseudo variable $this. $this is used to represent the current object or the object itself.

<?php 
class Person { 
// 人的成员属性 
var $name; //人的名字 
var $age; //人的年龄 
//人的成员 say() 方法 
function say() { 
echo "我的名字叫：".$this->name."<br />"; 
echo "我的年龄是：".$this->age; 
} 
} 
//类定义结束 
$p1 = new Person(); //实例化一个对象 
$p1->name = "Gonn"; //给 $p1 对象属性赋值 
$p1->age = 25; 
$p1->say(); //调用对象中的 say()方法 
?>

Program running result:

我的名字叫：Gonn 
我的年龄是：25

The above is the detailed content of Learn more about classes in php. For more information, please follow other related articles on the PHP Chinese website!