search
HomeBackend DevelopmentPHP TutorialIn PHP, subclasses overload parent class methods (parent::method name)

This article mainly introduces the relevant content of subclasses overloading parent class methods (parent::method name) in PHP. All are shared with everyone for your reference.

Overloading cannot be defined in PHP Functions with the same name also include methods with the same name that cannot be defined in the same class, so there is no method overloading. A method with the same name as the parent class can be defined in a subclass alone, because the methods of the parent class already exist in the subclass, so the methods inherited from the parent class can be overridden in the subclass.

The method of overriding the parent class in a subclass is to overwrite the methods inherited from the parent class in the subclass. Can’t the methods in the parent class be used directly if they are inherited by the subclass? Why do we need to overload it? Because there are some situations that we have to cover. For example, there is a "Bird" class, in which the general method "Fly" for birds is defined. Taking the "ostrich" class as its subclass will inherit the "flying" method, but as soon as the "flying" method in the "ostrich" class is called, the ostrich will fly away. Although ostriches cannot fly, other characteristics have the characteristics of "birds". Therefore, when declaring the "ostrich" class, you can still inherit the "bird" class, but you must add the "bird" class to the "ostrich" class. To rewrite the "flying" method inherited from the class, you need to overload the method in the parent class in the subclass.

In the following example, there is a "speak" method in the declared Person class. After the Student class inherits the Person class, it can directly use the "speak" method. However, the "speak" method in the Person class can only speak its own member attributes, while the Student class extends the Person class and adds several new member attributes. The code is as follows:

<?php
class Person{
protected $name;
protected $sex;
protected $Wage;
function __construct($name="",$sex="男",$age=1){
$this ->name = $name;
$this ->sex = $sex;
$this ->age = $age;
}
//在人类中声明一个通用的说话方法,介绍一下自己
function say(){
echo "我的名字:".$this-> name.",性别:".$this ->sex.",年龄:".$this ->age."。<br>";
}
}
//声明一个学生类,使用extends关键字扩展(继承)person类
class Student extends Person {
private $school; //在学生类中声明一个所在学校school的成员属性
//覆盖父类中的构造方法,在参数列表中添加一个学校属性,用来创建对象并初始化成员属性
function __construct($name="",$sex="男",$age=1,$school=""){
$this ->name = $name;
$this ->sex = $sex;
$this ->age = $age;
$this ->school = $school;
}
function study(){
echo $this ->name."正在".$this ->school."学习<br>";
}
//定义一个和父类中同名的方法,将父类中的说话方法覆盖并重写,多说出所在的学校名称
function say(){
echo "我的名字:".$this ->name.",性别:".$this ->sex.",年龄:".$this ->age.",在".$this ->school."学校上学<br>";
}
}
$student= new Student("张三","男",20,"edu"); //创建一个学生对象,并传给一个学校名称参数
$student -> say(); //调用学生类中覆盖父类的说话方法
?>

The output result after running the modified program is:

My name is: Zhang San, gender: male, my age is: 20, studying at edu school

In PHP, provided It has the function of calling the overridden method of the parent class in the overloaded method of the subclass. In this way, in the methods overridden by the subclass, you can continue to use the methods inherited from the parent class and overridden, and then add more new functions as required. The format of the call is to use "parent: method name" to call the overridden method in the parent class in the overloaded method of the subclass. Modify the code in the above example, use "parent::__construct()" in the overridden constructor of the subclass to call the overridden constructor of the parent class, and add an additional member attribute for the newly extended member of the subclass. Initialization code. Use "parent::say()" in the say() method overridden in the subclass to call the overridden say() method in the parent class, and then add the function of outputting the member attributes of the subclass.

The code is as follows:

<?php
class Person{
protected $name;
protected $sex;
protected $Wage;
function __construct($name="",$sex="男",$age=1){
$this ->name = $name;
$this ->sex = $sex;
$this ->age = $age;
}
//在人类中声明一个通用的说话方法,介绍一下自己
function say(){
echo "我的名字:".$this-> name.",性别:".$this ->sex.",年龄:".$this ->age."。<br>";
}
}
//声明一个学生类,使用extends关键字扩展(继承)person类
class Student extends Person {
private $school; //在学生类中声明一个所在学校school的成员属性
//覆盖父类中的构造方法,在参数列表中添加一个学校属性,用来创建对象并初始化成员属性
function __construct($name="",$sex="男",$age=1,$school=""){
//调用父类中被覆盖的构造方法,为从父类中集成过来额出行赋初值
parent::__construct($name,$sex,$age);
$this ->school = $school;
}
function study(){
echo $this ->name."正在".$this ->school."学习<br>";
}
//定义一个和父类中同名的方法,将父类中的说话方法覆盖并重写,多说出所在的学校名称
function say(){
parent::say(); //调用父类中被本方法覆盖掉的方法
echo "在".$this ->school."学校上学<br>";
}
}
$student= new Student("张三","男",20,"edu"); //创建一个学生对象,并传给一个学校名称参数
$student -> say(); //调用学生类中覆盖父类的说话方法
?>

The output result of the above example is the same as the previous example, but in this case In this example, it is much simpler to directly call the overridden method in the parent class in the subclass. In addition, when a subclass overrides a method of a parent class, it must be noted that the access permissions of the methods overridden in the subclass must not be lower than the access permissions of the overridden methods of the parent class. For example, if the access permission in the parent class is protected, then the permission of the method overridden in the child class must be protected or public.

Related recommendations:

Subclass overloading parent class method in PHP php annotation method php timing method php system authorizer

The above is the detailed content of In PHP, subclasses overload parent class methods (parent::method name). For more information, please follow other related articles on the PHP Chinese website!

Statement
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
php怎么把负数转为正整数php怎么把负数转为正整数Apr 19, 2022 pm 08:59 PM

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

php怎么实现几秒后执行一个函数php怎么实现几秒后执行一个函数Apr 24, 2022 pm 01:12 PM

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php怎么除以100保留两位小数php怎么除以100保留两位小数Apr 22, 2022 pm 06:23 PM

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

php怎么根据年月日判断是一年的第几天php怎么根据年月日判断是一年的第几天Apr 22, 2022 pm 05:02 PM

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php怎么判断有没有小数点php怎么判断有没有小数点Apr 20, 2022 pm 08:12 PM

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

php字符串有没有下标php字符串有没有下标Apr 24, 2022 am 11:49 AM

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

php怎么替换nbsp空格符php怎么替换nbsp空格符Apr 24, 2022 pm 02:55 PM

方法:1、用“str_replace("&nbsp;","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\&nbsp\;||\xc2\xa0)/","其他字符",$str)”语句。

php怎么读取字符串后几个字符php怎么读取字符串后几个字符Apr 22, 2022 pm 08:31 PM

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

See all articles

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 agoBy尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
1 months agoBy尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools