What's the difference between public function and public static function?

Question

OOP

I read a mountain of literature on OOP, I seem to have been working for more than a year, but static does not reach me. Here everything else comes, but there is no static. Why is it used?) I seem to have already forgotten about it, I usually always write in Laravel: And then I look at the code in the course, and among the exact same functions I see one like this: Its function in the code is used to add a comment on the site. And why not make it simple: What will go wrong in this case? Thank you!
public function xxx()
public static function add()
public function add()

Answer 1

If you do static:

class any_class
{
  public static function add()
  {
  }
}

... then, in order to use the method, it is not necessary to create an object, the class of which this method belongs to, it is available if there is a class description.
And so once again create an object for any reason in order to use the add () method.

class any_class
{
  public function add()
  {
  }
}

$any_class_object = new any_class;
$any_class_object->add();

If the methods are common, and are used for every sneeze, of course, it is beneficial to make them static.

Answer 2

Declaring the properties and methods of a class as static allows you to access them without creating an instance of the class. A class property declared as static cannot be accessed by an instance of the class (but a static method can be called).
Since static methods are called without creating an instance of the class, the $this pseudo-variable is not available inside a method declared as static.

Answer 3

Static methods and properties belong to a class, not to an object. The easiest way to explain this is with properties
class Foo {
static public $a = 0;
public $b = 0;
public function getA(){
return self::$a;
}
}
$Foo1 = new Foo;
$Foo2 = new Foo;
The property value "b" belongs to the object
$Foo1 -> b = 1;
echo $Foo2 -> b; // Outputs 0
The static property "a" belongs to the class and is available to any object of the class
Foo::$a = 15;
echo $Foo1 -> getA(); // 15
echo $Foo2 -> getA(); // fifteen