C++ Primer Plus

Class Scope Constants

Sometimes it would be nice to have symbolic constants with class scope. For example, a class declaration might use the literal 30 to specify an array size. Because the constant is the same for all objects, it would be nice to create a single constant shared by all objects. You might think the following would be a solution:

class Bakery{private:    const int Months = 12;    // declare a constant? FAILS    double costs[Months];    ...

But this won’t work because declaring a class describes what an object looks like but doesn’t create an object. Hence, until you create an object, there’s no place to store a value. (Actually, C++11 provides for member initialization, but not in a way that would make the preceding array declaration ...