I can declare constants that are used in that class.
To declare a constant, use the const keyword. Constants are declared in uppercase letters. Of course it's a promise.
const constant name = value;
self::constant name;
So let's declare and use a constant
<?php class Car { const TRUNK = true; public function checkTrunk() { return self::TRUNK; } } $car = new Car; if($car->checkTrunk() == true){ echo "This car has a trunk." ; } else { echo "This car has no trunk." ; } ?>
Result
To use a constant from a class outside the class, use instance ::.
Instance :: constant name;
<?php class Car { const TRUNK = true; public function checkTrunk() { return self::TRUNK; } } $car = new Car; if($car::TRUNK == true){ echo "This car has a trunk."; } else { echo "This car has no trunk."; } ?>
Of course, you must declare an instance so that you can use class constants outside the class.