Some knowledge points about PHP class

1. Class definition

<code class="hljs" xml=""><!--?php
class Cart{
   var $items;
   function add_item($artnr,$num){
      $this--->items[$artnr += $num;
   }
}</code>

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A class cannot be defined in multiple files, nor can the class definition be divided into multiple PHP blocks (it can be divided inside a function).
Cannot define a class named:
stdClass
__sleep
__wakeup
In fact, don't define classes starting with __.

2.Constructor

<code class="hljs" php="">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[&#39;firstname&#39;];
        /* etc. . . */
    }
}</code>

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If the class does not have a constructor, the base class constructor will be called.
Constructor parameters can be assigned default values

<code class="hljs" xml=""><!--?php
class Constructor_Cart extends Cart {
    function Constructor_Cart($item = 10, $num = 1) {
        $this--->add_item ($item, $num);
    }
}

// 买些同样的无聊老货
$default_cart = new Constructor_Cart;
// 买些实在货...
$different_cart = new Constructor_Cart(20, 17);
?></code>

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@new can suppress errors that occur in the constructor.

3. Use of classes

<code class="hljs" lasso="">$cart = new Cart;
$cart->add_item(10, 1);</code>

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The class uses $this internally to represent itself.

4. Class related functions

__autoload — Attempts to load an undefined class
call_user_method_array — Call a user method, passing an array of parameters (deprecated)
call_user_method — Call a user method on a specific object (deprecated)
class_alias — Create an alias for a class
class_exists — Check if a class is defined
get_called_class — The name of the "Late Static Binding" class
get_class_methods — Returns an array consisting of class method names
get_class_vars — Returns an array of default attributes of a class
get_class — Returns the class name of the object
get_declared_classes — Returns an array of names of defined classes
get_declared_interfaces — Returns an array containing all declared interfaces
get_declared_traits — Returns an array of all defined traits
get_object_vars — Returns an associative array of object properties
get_parent_class — Returns the parent class name of an object or class
interface_exists — Check if an interface has been defined
is_a — Returns TRUE
if the object belongs to this class or this class is the parent class of this object is_subclass_of — Returns TRUE
if this object is a subclass of this class method_exists — Check whether a class method exists
property_exists — Check if an object or class has the property
trait_exists — Check if the specified trait exists

5.Inheritance

<code class="hljs" php=""><!--?php
class Named_Cart extends Cart {
    var $owner;

    function set_owner ($name) {
        $this--->owner = $name;
    }
}
?></code>

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PHP does not support multiple inheritance.

6. Static method

<code class="hljs" php=""><!--?php
class A {
    function example() {
        echo I am the original function A::example().<br /-->
;
    }
}

class B extends A {
    function example() {
        echo I am the redefined function B::example().

;
        A::example();
    }
}

// A 类没有对象，这将输出
//   I am the original function A::example().

A::example();

// 建立一个 B 类的对象
$b = new B;

// 这将输出
//   I am the redefined function B::example().

//   I am the original function A::example().

$b->example();
?></code>

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7. Base class reference parent

<code class="hljs" php=""><!--?php
class A {
    function example() {
        echo I am A::example() and provide basic functionality.<br /-->
;
    }
}

class B extends A {
    function example() {
        echo I am B::example() and provide additional functionality.

;
        parent::example();
    }
}

$b = new B;

// 这将调用 B::example()，而它会去调用 A::example()。
$b->example();
?></code>

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8. Serialization

<code class="hljs" php=""><!--?php
// classa.inc:
  class A {
      var $one = 1;

      function show_one() {
          echo $this--->one;
      }
  }

// page1.php:
  include(classa.inc);

  $a = new A;
  $s = serialize($a);
  // 将 $s 存放在某处使 page2.php 能够找到
  $fp = fopen(store, w);
  fwrite($fp, $s);
  fclose($fp);

// page2.php:
  // 为了正常解序列化需要这一行
  include(classa.inc);

  $s = implode(, @file(store));
  $a = unserialize($s);

  // 现在可以用 $a 对象的 show_one() 函数了
  $a->show_one();
?></code>

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9. Magic function sleep wakeup

10. Allow array access to object properties

Method 1

function obj2array(obj){
return new ArrayObject(obj, ArrayObject::ARRAY_AS_PROPS);
}
This method is relatively simple, and the other method is a little more complicated to inherit ArrayAccess.

11. Convert array to object

<code class="hljs" php="">    /**
     * 数组转对象
     * @param unknown $e
     * @return void|StdClass
     */
    public static function arrayToObject($e){
        if( gettype($e)!=&#39;array&#39; ) return;
        foreach($e as $k=>$v){
            if( gettype($v)==&#39;array&#39; || getType($v)==&#39;object&#39; )
                $e[$k]=(object)arrayToObject($v);
        }
        return (object)$e;
    }</code>

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12 Self-implemented serialization and deserialization

It is more convenient when used in redis:

<code class="hljs" php="">    /**
     * 序列化对象，返回$json字符串
     */
    public static function serialize($model){
        //return serialize($model);
        if(!$model)return &#39;{}&#39;;
        $json=&#39;{&#39;;
        foreach($model as $key2=>$value2){
            if($json!=&#39;{&#39;)$json.=&#39;,&#39;;
            $json.=$key2:$value2;
        }
        $json.=&#39;}&#39;;


        return $json;
    }
    public static function unserialize($json){
        $json=str_replace(&#39;{&#39;, &#39;&#39;, $json);
        $json=str_replace(&#39;}&#39;,&#39;&#39;,$json);
        $array=explode(&#39;,&#39;, $json);
        $result=[];
        foreach($array as $key =>$value){
            $temparr=explode(&#39;,&#39;,$value);
            $temparr1=explode(&#39;:&#39;,$temparr[0]);

            if(count($temparr1)==0)continue;
            $result[$temparr1[0]]=trim( $temparr1[1],&#39;&#39;);
        }
        //$obj=  (object)($result);

        return obj2array($result);
        //return $result;
    }</code>

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