Detailed explanation of objects in PHP introductory tutorial (1/5)_PHP tutorial

Objects in PHP include many contents, such as the most commonly used PHP classes, interfaces, polymorphic magic methods (:_construct(), _destruct(), _clone), etc.

Class declaration:

The code is as follows

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代码如下	复制代码
权限修饰符 class 类名{ //权限修士符号:public,protected,private 或者省略3者. 　　　　　　//类体;　　　　　　　　//class 是建类关键字 　　　　}　　　　　　　　　　　　　//类名必须跟在class 后面,且跟上{}.{}之间放类的成员. 　　?> //ps:在class关键字前可以加权限修饰符外,还可以加static,abstract等关键字.一个类,即一对大括号之间的全部内容都要在一段代码段中,不允许将类中的内容分割成对块. 　　class ConnDB{ 　　　　//.... ?> 　　　　//... 　　}; ?>

Permission modifier class class name { //Permission monk symbol: public, protected, private or omit 3.
//Class body; //class is the keyword to create a class
　　　　　　　　　　 //The class name must follow class, and the members of the class must be placed between {}.{}.
​?>
//ps: In addition to the permission modifier before the class keyword, you can also add static, abstract and other keywords. A class, that is, all the content between a pair of curly brackets must be in a piece of code. It is not allowed to include The content in the class is divided into pairs of blocks.
class ConnDB{
​ //....
?>

　　 //...
};
?>

Member attributes:

Variables declared directly in a class are called member attributes/variables. Their types can be scalar types and composite types in PHP. Using resource types and empty types is invalid.

In addition, when declaring member attributes, they must be modified with keywords: keywords with specific meanings: public, protected, private; no specific meaning is required: var. When declaring member attributes, there is no need to assign an initial value.

Member constants:

Modified with const constants, for example: const PI = 3.1415926;

The output of constants does not need to be instantiated. It can be called directly by class name + constant name. The format is: class name::constant name

ps. Special access methods:--------"$this" and "::"

1) $"this" exists in each member method. It is a special object to use methods. The member method belongs to that object, and $this application represents that object. Its function is to specifically complete the internal members of the object. visit.

2) "::" becomes the scope operator. Use this operator to call constants, variables and methods in the class without creating an object. Its syntax format is as follows:

Keywords:: variable name/constant name/method name

Keyword: parent, you can call member variables, member methods and constants in parent class members;

　Self, you can call static members and constants in the current class;

Class name, you can call constants, variables and methods in the class;

　

Member methods:

Functions declared in a class become member methods. Multiple functions can be declared in a class, that is, an object can have multiple member methods. The declaration of a member method is the same as the declaration of a function. The only special thing is that the member method can There are keywords to modify it to control its access rights.

Instantiation of class

Create object:

　$Variable name = new class name([parameter]); //Instantiation of the class.

Access class members:

　$Variable name -> member attribute = value; 1 2 3 4 5 http://www.bkjia.com/PHPjc/629071.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/629071.html

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Objects in php include many contents, such as the most commonly used php classes, interfaces, polymorphic magic methods (:_construct (),_destruct(),_clone), etc. Class declaration: The code is as follows Copy code ?php permission modification...