How do I define a class in PHP? A method of defining a class in PHP

What this article brings to you is about how to define a class in PHP. PHP definition of a class method, there is a certain reference value, the need for friends can refer to, I hope to help you.

Object-oriented Basic concepts

Consists of 3 parts:

Object-oriented analysis (oriented ANALYSIS,OOA)

Object-oriented designing (object oriented Design,ood)

Object-oriented programming (object oriented Programming,oop)

Definition of Class

A class is a collection of properties and methods "human, animal, plant"

property, which is a variable defined within a class, also known as a member property, member variable.

method, which is a function defined within a class.

What do you need to learn?

How do I define a class?

<?php//keyword class  +  class name class person () {}

How do I instantiate a class?

<?phpclass person () {}//object = keyword  class name (); $person =new Man ();

How do I tune one of the methods in a class?

<?phpclass person () {        function run () {        echo "I'm Running";    }} $person =new person (); $person->run ();//Run Result: My method in the Run//object--Class

How do I tune variable information in a class?

<?phpclass person () {public        $name = "Shanyun";} $person =new person (); Echo $person->name ();//Run Result: Shanyun//Object-class variable name (note there is no $)

Definition of Object

An object is a concrete instantiation of an entity

Relationship of classes and objects

What are the modifiers for a variable?

Public: Common, attributes can be used outside of the class

Protected: Protected, properties can only be used inside the class (if there is inheritance, it may be used inside the subclass)

Private: Privately, can only be used inside the current class, and cannot be used anywhere else

Note: The default is the public modifier when the method is not in front of it;

Three main features of object-oriented

Encapsulation, inheritance, polymorphism

Encapsulation, also known as information hiding, classes retain only limited interfaces and external connections. Know how to invoke a method without worrying about how to implement the details.

inheritance, derived classes automatically inherit properties and methods from the parent class, improving code reusability. Extends

Polymorphism, refers to a class of different objects call the same method can get different results. Enhanced flexibility and reusability of the system.

After-school assignments:

Define a student class Student

1. Define attributes: Number (ID), name (name), Gender (sex).

2. Define public call methods: Say () output I'm Zhang San, sex guy, number 004.