The difference between -> and :: in PHP
The difference between -> and :: in PHP
->
Methods and attributes in a class used to reference class instances
For example:
class Test{
function add(){return $this->var++;}
var $var = 0;
}
$a = new Test; // 实例化对象名称
echo $a->add();
echo $a->var; ::
Reference methods of static methods and static properties in classes
For example:
class Test{
public static function test(){
public static $test = 1;
}
}Static methods and static properties of a class can be used directly without instantiating the object (the method used is class name::static method name)
Test::test(); // 调用静态方法test Test::$test; // 来取得$test静态属性的值
Note:
Static methods are used after reading this class or introducing them When this class file is created, it has already been instantiated and stored in memory. Non-static classes need to be new.
Even if a static class has multiple instances in memory, there is only one copy of the static attributes.
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