Encapsulation, inheritance, class static methods, static properties of PHP functions, classes and objects, and classes

Original: PHP functions, classes and objects, and class encapsulation, inheritance, class static methods, static properties

1. Functions

PHP built-in functions can be used directly, if not installed PHP extension can be

Custom functions

//   functional Function    function Dump ($varnull) {    // expense default parameter value        echo ' < Pre/>';          Var_dump ($var);    }

2. Classes (Class) and objects (new OBJ)

<?  // Define a person's class, not now object class//

    Private $eye= ' Big Eyes '; Private $mouth= ' small Mouth '; Private $leg= ' Big long legs '; //custom Call when constructing method new Object     Public function__construct () {Echo __class__; }         Public functionrun () {Echo  $this-leg; }     //Learning uses legs (walking), eyes (Reading), mouth (studying)     Public functionStudy () {Echo $this->leg,$this->eye,$this-mouth; }                 }//after using class new, it becomes an object.$person=NewPerson ();//Output Person$personRun ();//large long leg output$personStudy ();//output big long legs big eyes small lips

3. Encapsulation of classes (public, protected, private) and inheritance (extends)

//Inheritance of Classesclassa{ Public functionHelp () {Echo __method__; }    //declare a way to eat private    Private functioneat () {Echo  __method__; }}//subclasses can inherit all public methods and properties of the parent class, protected methods and properties, except private methods//If you want to use them, override themclassBextendsa{ Public functiondosomething () {$thisHelp ();//The method that inherits the parent class is declared as public        Echo' ; $thisEat ();//because eating is private and subclasses are not available, a Eat method is written in the subclass.    }    //sub-class eating     Public functioneat () {Echo __method__; }}$b=NewB;$b->dosomething ();

Output results

A::help

B::eat

4. Static methods and static properties of classes

<?PHP//define a URL-related classclassurl{ Public Static functionCreateURL ($arr= [])    {        Echo __method__; }     Public Static functionredirect$url= ' ')    {        Echo __method__; }     Public Static functionGetcurrenturl () {Echo __method__; }}//declare methods as static methods, do not need to instantiate each time (new) object, easy to operate, save memory, more efficientEchoUrl::createurl ($var= ' ');EchoUrl::redirect ($url= ' ');EchoUrl::getcurrenturl ();

5. Static properties of the class

<?PHP//define a URL-related classclassurl{//declared as a class constant    ConstURL = ' http://www.baidu.com ';//You can use the const//declaration as a static variable directly outside of the class since 5.3      Public Static $var= ' It is very good ';  Public Static functionCreateURL ($arr= [])    {        EchoSelf::URL; Echo' <br/> '; EchoSelf::$var; Echo' <br/> '; Echo __method__; }     Public Static functionredirect$url= ' ')    {        Echo __method__; }     Public Static functionGetcurrenturl () {Echo __method__; }}//declare methods as static methods, do not need to instantiate each time (new) object, easy to operate, save memory, more efficientEchoUrl::createurl ($var= ");

Encapsulation, inheritance, class static methods, static properties of PHP functions, classes and objects, and classes