php的静态变量解释，实例代码

class A{
  var $b = 0;
  static private $c = 0;
  public function test(){
     $this->b ++;
     self::$c ++;
  }
  public function out(){
    echo $this->b, "\n", self::$c, "\n";
  }
}
$b = new A;
$c = new A;
$b->test();  //b=1,c=1
$b->test();  //b=2,c=2
$c->test();  //b=1,c=3
$b->out();
$c->out();