Rules for implicit default constructors

• you add a constructor taking no arguments:

class Point {
public:
    Point();
};

• you add a constructor with all default arguments:

class Point {
public:
    Point( int x = 0, int y = 0 );
};

• you add a constructor taking one or more arguments:

class Point {
public:
    Point( Point const* other );
};
void main()
{
    Point pt; // Error: no default constructor:
}