.net – When should I use a struct instead of a class

The differences between a class and a struct in C++ is:

• struct members and base classes/structs are public by default.
• class members and base classes/struts are private by default.

Both classes and structs can have a mixture of public, protected and private members, can use inheritance and can have member functions.

I would recommend you:

• use struct for plain-old-data structures without any class-like features;
• use class when you make use of features such as private or protected members, non-default constructors and operators, etc.

Variables declared inside the class definition, but not inside a method are class or static variables:

>>> class MyClass:
...     i = 3
...
>>> MyClass.i
3 

As @millerdev points out, this creates a class-level i variable, but this is distinct from any instance-level i variable, so you could have

>>> m = MyClass()
>>> m.i = 4
>>> MyClass.i, m.i
>>> (3, 4)

This is different from C++ and Java, but not so different from C#, where a static member can't be accessed using a reference to an instance.

See what the Python tutorial has to say on the subject of classes and class objects.

@Steve Johnson has already answered regarding static methods, also documented under "Built-in Functions" in the Python Library Reference.

class C:
    @staticmethod
    def f(arg1, arg2, ...): ...

@beidy recommends classmethods over staticmethod, as the method then receives the class type as the first argument, but I'm still a little fuzzy on the advantages of this approach over staticmethod. If you are too, then it probably doesn't matter.