PHP: Detailed explanation of object data type instances

What is an object?

Objects are data types that store data and information about how to process the data. It is an entity used to describe objective things in the system. It is a basic unit that constitutes the system. An object consists of a set of properties and a set of services that operate on the set of properties.

Syntax

In PHP, objects must be declared explicitly.

First we must declare the class of the object. We use the keyword class to declare a class, followed by the name of the class, and the body is enclosed in {} symbols. Think of it like this

class class_name{
    ......
}

The class contains attributes and methods.

Attributes

By using the keyword var in the class definition to declare variables, the attributes of the class are created, also called member attributes of the class.

Grammar:

class class_name{
    var $var_name;
}

For example, if you define a human class, then the person’s name, age, gender, etc. can be regarded as the human class. Attributes.

Method

By declaring a function in the class definition, a method of the class is created.

Grammar:

class class_name{
    function function_name(arg1,arg2,……)
    {
        函数功能代码
    }
}

Application of classes

A class that defines properties 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.

Syntax:

object = new class_name();

After instantiating an object, use the -> operator to access the object's member properties and methods.

Syntax:

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.

Example:

<?php
header("content-type:text/html;charset=utf-8");
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 "我的网址是：".$this->age;
    }
}    //类定义结束
//实例化一个对象
$p1 = new Person();
//给 $p1 对象属性赋值
$p1->name = "PHP中文网";
$p1->age = &#39;www.php.cn&#39;;
//调用对象中的 say()方法
$p1->say();
?>

Run this example, output:

The above is a simple example of our composite data type "object", about For more knowledge about objects, please visit our Object Topics, In the next section, we will explain the "Resources"# among the two special data types in PHP ##

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