C++ providing default parameters to constructors - c++

Question

In the c++ class below, I've provided default parameters to the constructor in case the user does not provide one. However, when I for example Point2d1 first(1, 0); in main() I get an error of no matching function call. I expected the behavior to default the 3rd parameter to 0?
.h
#ifndef POINT2D1_H_
#define POINT2D1_H_
class Point2d1 {
private:
int m_Object_ID;
double m_x;
double m_y;
public:
//Point2d1(int nID);
Point2d1(int nID, double x, double y);
virtual ~Point2d1();
void print() const;
friend double distanceFrom(const Point2d1& D1, const Point2d1& D2);
};
#endif /* POINT2D1_H_ */
.cpp
Point2d1::Point2d1(int nID = 0, double x = 0.0, double y = 0.0) : m_Object_ID(nID), m_x(x), m_y(y)
{
std::cout << "Constructing Point2d object " << nID << '\n';
}
Point2d1::~Point2d1() {
std::cout << "Destructing Object" << '\n';
}
void Point2d1::print() const
{
std::cout << "Point2d(" << m_x << ", " << m_y << ")\n";
}
double distanceFrom(const Point2d1& D1, const Point2d1& D2)
{
double distance = sqrt((D1.m_x - D2.m_x)*(D1.m_x - D2.m_x) + (D1.m_y - D2.m_y)*(D1.m_y - D2.m_y));
return distance;
}

Answer 1

Declare the default arguments in the member function declartion inside the class definition in the header file. Otherwise other compilation units will not know about the default arguments.
For example
.h
#ifndef POINT2D1_H_
#define POINT2D1_H_
class Point2d1 {
//...
public:
//Point2d1(int nID);
Point2d1(int nID = 0, double x = 0.0, double y = 0.0);
//...
};
#endif /* POINT2D1_H_ */
and
.cpp
Point2d1::Point2d1(int nID, double x, double y) : m_Object_ID(nID), m_x(x), m_y(y)
{
std::cout << "Constructing Point2d object " << nID << '\n';
}