PHP中=＞、-＞、::的用法记录

☆=>

$css = array('style' => '0', 'color' => 'green');
$css['style']==='0',$css['color']=='green';

☆->

$arr=['a'=>123,'b'=>456];//数组初始化
echo $arr['a'];//数组引用
print_r($arr);//查看数组
class A{
  public $a=123;
  public $b=456;
}
$obj=new A();
echo $obj->a;//对象引用
print_r($obj);//查看对象

☆::
双冒号操作符即作用域限定操作符Scope Resolution Operator可以访问静态、const和类中重写的属性与方法。

（1）Program List：用变量在类定义外部访问

class Fruit {
  const CONST_VALUE = 'Fruit Color';
}
$classname = 'Fruit';
echo $classname::CONST_VALUE; // As of PHP 5.3.0
echo Fruit::CONST_VALUE;

（2）Program List：在类定义外部使用::

class Fruit {
  const CONST_VALUE = 'Fruit Color';
}
class Apple extends Fruit{
  public static $color = 'Red';
  public static function doubleColon() {
    echo parent::CONST_VALUE . "\n";
    echo self::$color . "\n";
  }
}
Apple::doubleColon();

（3）Program List：调用parent方法

class Fruit{
  protected function showColor() {
    echo "Fruit::showColor()\n";
  }
}
class Apple extends Fruit{
  // Override parent's definition
  public function showColor(){
    // But still call the parent function
    parent::showColor();
    echo "Apple::showColor()\n";
  }
}
$apple = new Apple();
$apple->showColor();

（4）Program List：使用作用域限定符

class Apple{
  public function showColor(){
    return $this->color;
  }
}
class Banana12{
  public $color;
  public function __construct(){
    $this->color = "Banana is yellow";
  }
  public function GetColor(){
    return Apple::showColor();
  }
}
$banana = new Banana;
echo $banana->GetColor();

（5）Program List：调用基类的方法

class Fruit{
  static function color(){
    return "color";
  }
  static function showColor(){
    echo "show " . self::color();
  }
}
class Apple extends Fruit{
  static function color(){
    return "red";
  }
}
Apple::showColor();
// output is "show color"!