Static Member Functions

// static_member_functions.cpp
#include <stdio.h>

class StaticTest
{
private:
    static int x;
public:
    static int count()
    {
        return x;
    }
};

int StaticTest::x = 9;

int main()
{
    printf_s("%d\n", StaticTest::count());
}

9

In the preceding code, the class StaticTest contains the static member function count. This function returns the value of the private class member but is not necessarily associated with a given object of type StaticTest.

Static member functions have external linkage. These functions do not have this pointers. As a result, the following restrictions apply to such functions:

• They cannot access nonstatic class member data using the member-selection operators (. or –>).

• They cannot be declared as virtual.

• They cannot have the same name as a nonstatic function that has the same argument types.

  Note
  The left side of a member-selection operator (. or –>) that selects a static member function is not evaluated. This can be important if the function is used for its side effects. For example, the expression SideEffects().CountOf() does not call the function SideEffects.

Reference