I want to ask if both are the same and if not, where's the difference between them:
/**
* @param int|null $id Any id.
*/
public function testSomething(int $id = null) {}
and
/**
* @param int|null $id Any id.
*/
public function testSomething(?int $id) {}
Thank you for your answer!
It's different. The first function declaration :
public function testSomething(int $id = null) {}
sets the default value to null, if you call the function without an argument.
The second definition :
public function testSomething(?int $id) {}
will accept a null value as the first argument, but does not set it to a default value if the argument is missing. So you always need to have an argument if you call the function in the second way.
It's different. The first declaration use implicit nullable :
public function testSomething(int $id = null) {} // Only default value set to null
Note that this type of declaration is deprecated since PHP 8.4
You should instead use explicitly nullable which can be written in two ways:
public function testSomething(?int $id = null) {} // With the '?' marker
or
public function testSomething(int|null $id = null) {} // With the '|null' union type
About those these two in PHP 8.4: Implicitly nullable parameter declarations deprecated:
Both type declarations are effectively equivalent, even at the Reflection API. The second example is more verbose, and only works on PHP 8.0 and later.
testSomething(?int $id) {}without arguments - will probably throw a fatal error, whereas you can invoke the first casetestSomething(int $id = null) {}without arguments.