Object-oriented PHP

I. Defining classes

• • format: class classname  [extendsclass] {varproperty  = value;        // Properties function functionname (args) {     // method    /code }}

Second, create the object

• Creating objects using the New keyword

• $obj=new person ();

Third, get the object in the class

• Echo $obj // Get Properties in a class $obj // calling methods in a class

Four, const constants

• You can define constants in a class, that is, values that do not change in the class. For any object instantiated from this class, constant values remain unchanged throughout the life cycle of those objects.
• The class constants are created as follows:

• Const NAME = ' value '; for example:constPI = 3.1415926;

• echo self::pi// class internal access echo math_function::pi//  class external Access

static properties and Static methods

• You can use the static keyword to identify member properties or to identify member methods.
• Here's how to create it:

• Static $test _static // Properties Static function  // method }

• Declaring a class property or method as static can be accessed directly without instantiating the class
• Static methods do not need to be called through an object, so the pseudo-variable $this is not available in a static method.
• A static property cannot be accessed by an object through the operator.
• Note: Static members belong to class-owned, so we cannot use $this to refer to static members in static methods, we recommend using the Self keyword to invoke.
• For example:

•  class   test{ static   $a  = ' static ' < span> static  function   m () { return  self:: $a ; //   }}   $a ; //     External access property  echo  Test::m (); //
   external access method  

VI, Inherit public--public property, can freely access private--private property or method only in their own class can use protected--protected properties: Only in their own class and subclasses can call

Prototype Properties--Implementing inheritance

Object-oriented PHP