What is the difference of const and static const?

Question

The following statements are both valid:

static const A = 2;
const B = 3;

What is the difference of declaring the first or the second?

Answer 1

If the static const were to be declared inside a class it'd accesible from the class and any instance of the class, so all of the would share the same value; and the const alone will be exclusive for every instance of the class.

Given the class:

class MyClass {
    public:
        static const int A = 2;
        const int B = 4;
};

You can do this:

int main() {
    printf("%d", MyClass::A);

    /* Would be the same as */

    MyClass obj;
    printf("%d", obj.A);

    /* And this would be illegal */
    printf("%d", MyClass::B);
}

Check it out here on Ideone.

Answer 2

Static means the entire class only shares 1 const, where non-static means every instance of the class has that const individually.

Example:

class A{

static const a;
const b; 
}

//Some other place:

A m;
A n;

Objects m and n have the same a, but different b.