Abstract classes and interfaces in PHP

Instantiates a class to produce an object.
Class Fenbi
//{
Ordinary member, belonging to the object
Public $length = "10cm";
Static member, static variable, belongs to class.
public static $color;
//
Normal methods can call static members
function Hua () {
Echo $this->length;
echo self:: $color;
// }
Static methods cannot call ordinary members
static function Hua2 () {
echo self:: $color;
// }
//}
Instantiating an object calls a normal member
$FB = new Fenbi ();
$FB->hua ();
echo "<br>";
Invoke static members with Thunder
Fenbi:: $color = "Red";
FENBI::HUA2 ();
echo "<br>";
$FB 2 = new Fenbi ();
$FB 2->hua ();

Abstract class: Abstraction
Features: cannot be instantiated, can only be inherited
Purpose: In order to derive subclasses, control the sub-class
For writing base classes
Abstract class Ren
//{
Public $name;
//
function speak () {
echo "is talking";
// }
//}
$chinese = new Ren (); This is wrong, not so, cannot be instantiated;
Class Chinese extends ren{

//}

Interface
Class of extreme Abstraction
Interface cannot contain member variables, only member methods
Member methods have no function body
Interface Keyword: interface name Capital I start
Interface must implement all the methods inside
Interface Iusb 
  {
  public function read  () ; 
  public function write  () ; 
 } 
 class  mouse implements  iusb 
  {
   function read  () 
  {
 } 
  function write  () 
  {
 } 
 }   

Abstract classes and interfaces in PHP