Creating an instance of a class within a class (C++)

Question

Let's say I have two classes: Box, Circle.

class Box{
int x, y;
...Box(int xcoord, int ycoord){printf("I'm a box."); x = xcoord; y = ycoord;}
};

class Circle{
...Circle(){printf("I'm a circle.");}
};

But let's say in the Circle class, I want to make an instance of the Box class. Well I tried this:

class Circle{
Box b(0,0);
...Circle(){printf("I'm a circle.");}
};

I get an error:

error C2059: syntax error : 'constant'

Answer 1

class Circle {
    Box b;

public:
    Circle() : b(0, 0)
    {
        printf("I'm a circle.");
    }
};