Some knowledge points of the PHP class

1. Definition of class

<?phpclass Cart{   var $items;   function add_item($artnr,$num){      $this->items[$artnr += $num;   }}

A class cannot be defined in more than one file, nor can a class definition be divided into multiple PHP blocks (inside a function).
You cannot define a class named the following:
StdClass
__sleep
__wakeup
In fact, do not define classes with __.

2. Constructors

 class Cart {    var $todays _date;var $name;var $owner;var $items=Array("VCR","TV"); function Cart() {        $this->todays_date = Date ("Y-m-d");$this->name =$GLOBALS[' FirstName '];/ * Etc ... * /}}

Class if there is no constructor, the base class constructor is called.
Constructor parameters can be assigned default values

<?php class constructor_cart extends Cart {     function constructor_cart($item = "Ten", $num = 1) {        $this->add_item ($item,$num); }}//Buy some of the same boring old goods$default _cart=NewConstructor_cart;//Buy some real goods ...$different _cart=NewConstructor_cart ("a", -);?>

@new can suppress errors that occur in the constructor.

3. Use of Classes

$cart=new Cart;$cart->add_item("10"1);

Within the class, use $this to represent itself.

4. Class-related functions

__autoload-attempting to load an undefined class
call_user_method_array-invokes a user method, passing a parameter array (deprecated)
Call_user_method-invoking a user method on a specific object (deprecated)
class_alias-Creating an alias for a class
class_exists-checking whether a class is defined
get_called_class-Late static binding ("late static binding") class name
get_class_methods-returns an array of the method names of the class
get_class_vars-returns an array that consists of the default properties of the class
get_class-returns the class name of the object
get_declared_classes-returns an array consisting of the names of the defined classes
get_declared_interfaces-returns an array containing all the declared interfaces
get_declared_traits-returns an array of all defined traits
get_object_vars-returns an associative array consisting of object properties
get_parent_class-returns the parent class name of an object or class
interface_exists-Check if the interface has been defined
is_a-returns TRUE if the object belongs to the class or if the class is the parent class of this object
is_subclass_of-returns TRUE If this object is a subclass of the class
method_exists-checking the existence of a class's methods
property_exists-checking whether an object or class has this property
trait_exists-checks if the specified trait exists

5. Inheritance

<?phpclass Named_Cart extends Cart {    var$owner;    function set_owner ($name) {        $this$name;    }}?>

PHP does not support multiple inheritance.

6. Static methods

<?php class A {     function example() {        Echo "I am the original function a::example (). <br/>\n"; }} class B extends A {     function example() {        Echo "I am the redefined function b::example (). <br/>\n";    A::example (); }}The //class A does not have an object, which outputs//I AM the original function a::example (). <br/>A::example ();//Create an object of class B$b=NewB//This will output//I AM the redefined function b::example (). <br/>//I AM the original function a::example (). <br/>$b->example ();?>

7. base class Reference Parent

<?php class A {     function example() {        Echo "I am a::example () and provide basic functionality.<br/>\n"; }} class B extends A {     function example() {        Echo "I am b::example () and provide additional functionality.<br/>\n";Parent:: Example (); }}$b=NewB//This will call B::example (), and it will go to call A::example (). $b->example ();?>

8. Serialization

<?php//Classa.inc:   class A {      var $one=1; function show_one() {          Echo $this->one; }  }//page1.php:  include("Classa.inc");$a=NewA$s= Serialize ($a);//Store $s somewhere so page2.php can find  $fp= fopen ("Store","W"); Fwrite$fp,$s); Fclose$fp);//page2.php:  //This line is required for normal deserialization  include("Classa.inc");$s= Implode ("", @file ("Store"));$a= Unserialize ($s);//You can now use the Show_one () function of $a object.  $a->show_one ();?>

9. Magic function __sleep __wakeup10. Allow array mode access to object Properties Method 1

function Obj2array (obj) {
return new Arrayobject (obj, arrayobject::array_as_props);
}
This method is relatively simple, and another way to inherit arrayaccess is a bit more complicated.

11. Array to Object

    /** * Array to Object * @param Unknown $e * @return void| StdClass * *     Public Static  function arraytoobject($e){        if(GetType ($e)!=' array ')return;foreach($e  as $k=$v){if(GetType ($v)==' array '|| GetType ($v)==' object ')$e[$k]= (object) Arraytoobject ($v); }return(object)$e; }

12 self-implemented serialization and deserialization

Easy to use with Redis:

    /** * Serialize object, return $json String * /     Public Static  function serialize($model){        //return Serialize ($model);        if(!$model)return ' {} ';$json=' {';foreach($model  as $key 2=$value 2){if($json!=' {')$json.=', ';$json.=" $key 2:\" $value 2\ ""; }$json.='} ';return $json; } Public Static  function unserialize($json){        $json=str_replace (' {',"',$json);$json=str_replace ('} ',"',$json);$array=explode (', ',$json);$result=[];foreach($array  as $key=$value){$temparr=explode (', ',$value);$temparr 1=explode (': ',$temparr[0]);if(Count ($temparr 1)==0)Continue;$result[$temparr 1[0]]=trim ($temparr 1[1],' "'); }//$obj = (object) ($result);        returnObj2array ($result);//return $result;}

Reference:
http://php.net/manual/zh/oop4.php

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Some knowledge points of the PHP class