What's the difference between :: (double colon) and -> (arrow) in PHP?

Question

There are two distinct ways to access methods in PHP, but what\'s the difference?

$response->setParameter(\'foo\', \'bar\');

and

Answer 1

Actually by this symbol we can call a class method that is static and not be dependent on other initialization...

class Test {

    public $name;

    public function __construct() {
        $this->name = 'Mrinmoy Ghoshal';
    }

    public static function doWrite($name) {
        print 'Hello '.$name;
    }

    public function write() {
        print $this->name;
    }
}

Here the doWrite() function is not dependent on any other method or variable, and it is a static method. That's why we can call this method by this operator without initializing the object of this class.

Test::doWrite('Mrinmoy'); // Output: Hello Mrinmoy.

But if you want to call the write method in this way, it will generate an error because it is dependent on initialization.