Home Backend Development PHP Tutorial Revealing the secrets of using PHP constructor_PHP tutorial

Revealing the secrets of using PHP constructor_PHP tutorial

Jul 15, 2016 pm 01:27 PM
php one learn Instructions about function develop publish Multi-user I Reveal

After a long period of development of PHP, many users know PHP very well. Here I will express my personal understanding and discuss it with everyone. Most classes have a special method called a constructor. When an object is created, it will automatically call the PHP constructor, that is, the constructor method will be automatically called when the new keyword is used to instantiate the object.

The declaration of the PHP constructor is the same as the declaration of other operations, except that its name must be __construct(). This is a change in PHP5. In previous versions, the name of the constructor must be the same as the class name. This can still be used in PHP5, but now few people use it. The advantage of this is that the constructor can be Independent of the class name, there is no need to change the corresponding constructor name when the class name changes. For backward compatibility, if there is no method named __construct() in a class, PHP will search for a constructor method written in php4 with the same name as the class name. Format: function __construct ([parameter]) { ... ... } Only one constructor method can be declared in a class, but the constructor method will only be called once every time an object is created. This method cannot be called actively, so usually Use it to perform some useful initialization tasks. For example, the corresponding properties are assigned initial values ​​when the object is created.
<ol class="dp-xml">
<li class="alt"><span><span>//创建一个人类  </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span>0class Person   </span></li>
<li class=""><span>0{   </span></li>
<li class="alt"><span>//下面是人的成员属性   </span></li>
<li class=""><span>var $name;       //人的名子   </span></li>
<li class="alt"><span>var $sex;        //人的性别   </span></li>
<li class=""><span>var $age;        //人的年龄   </span></li>
<li class="alt"><span>//定义一个构造方法参数为姓名$name、性别$sex和年龄$age   </span></li>
<li class=""><span>function __construct($name, $sex, $age)   </span></li>
<li class="alt"><span>{   </span></li>
<li class="">
<span>//通过构造方法传进来的$name给成员属性$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>name赋初使值   </span>
</li>
<li class="alt">
<span>$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span class="attribute"><font color="#ff0000">name</font></span><span>=$name;   </span>
</li>
<li class="">
<span>//通过构造方法传进来的$sex给成员属性$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>sex赋初使值   </span>
</li>
<li class="alt">
<span>$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span class="attribute"><font color="#ff0000">sex</font></span><span>=$sex;   </span>
</li>
<li class="">
<span>//通过构造方法传进来的$age给成员属性$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>age赋初使值   </span>
</li>
<li class="alt">
<span>$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span class="attribute"><font color="#ff0000">age</font></span><span>=$age;   </span>
</li>
<li class=""><span>}   </span></li>
<li class="alt"><span>//这个人的说话方法   </span></li>
<li class=""><span>function say()   </span></li>
<li class="alt"><span>{  </span></li>
<li class="">
<span>echo "我的名子叫:".$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>name." 性别:".$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>sex." 我的年龄是:".$this-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>age."</span><strong><font color="#006699"><span class="tag"><</SPAN><SPAN class=tag-name>br</SPAN><SPAN class=tag>></span></font></strong><span>";   </span>
</li>
<li class="alt"><span>}   </span></li>
<li class=""><span>}   </span></li>
<li class="alt"><span>//通过构造方法创建3个对象$p1、p2、$p3,分别传入三个不同的实参为姓名、性别和年龄  </span></li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">p1</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">new</font></span><span> Person("张三","男", 20);   </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">p2</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">new</font></span><span> Person("李四","女", 30);   </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">p3</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">new</font></span><span> Person("王五","男", 40);   </span>
</li>
<li class="alt"><span>//下面访问$p1对象中的说话方法   </span></li>
<li class="">
<span>$p1-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>say();   </span>
</li>
<li class="alt"><span>//下面访问$p2对象中的说话方法   </span></li>
<li class="">
<span>$p2-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>say();   </span>
</li>
<li class="alt"><span>//下面访问$p3对象中的说话方法   </span></li>
<li class="">
<span>$p3-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>say();   </span>
</li>
</ol>
Copy after login



The output result is:
My name is: Zhang San Gender: Male My age is: 20
My name is: Li Si Gender: Female My age is: 30
My name is: Wang Wu Gender: Male My age is: 40


www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/446532.htmlTechArticleAfter a long period of development of PHP, many users know PHP very well. Here I will express my personal understanding and share it with you. Discuss discuss. Most classes have a special method called a constructor. ...
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

CakePHP Project Configuration CakePHP Project Configuration Sep 10, 2024 pm 05:25 PM

In this chapter, we will understand the Environment Variables, General Configuration, Database Configuration and Email Configuration in CakePHP.

PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian Dec 24, 2024 pm 04:42 PM

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

CakePHP Date and Time CakePHP Date and Time Sep 10, 2024 pm 05:27 PM

To work with date and time in cakephp4, we are going to make use of the available FrozenTime class.

CakePHP File upload CakePHP File upload Sep 10, 2024 pm 05:27 PM

To work on file upload we are going to use the form helper. Here, is an example for file upload.

CakePHP Routing CakePHP Routing Sep 10, 2024 pm 05:25 PM

In this chapter, we are going to learn the following topics related to routing ?

Discuss CakePHP Discuss CakePHP Sep 10, 2024 pm 05:28 PM

CakePHP is an open-source framework for PHP. It is intended to make developing, deploying and maintaining applications much easier. CakePHP is based on a MVC-like architecture that is both powerful and easy to grasp. Models, Views, and Controllers gu

How To Set Up Visual Studio Code (VS Code) for PHP Development How To Set Up Visual Studio Code (VS Code) for PHP Development Dec 20, 2024 am 11:31 AM

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

CakePHP Creating Validators CakePHP Creating Validators Sep 10, 2024 pm 05:26 PM

Validator can be created by adding the following two lines in the controller.

See all articles