出口超负荷经营者

Question

I've created (in Qt and Mingwin the specified case), a class that has the following structure:

#ifndef POINT2D_H
#define POINT2D_H

#include "Calculus_global.h"
#include <QtCore>

namespace Calculus
{

/** Class for definition of a point in 2D space */
class CALCULUSSHARED_EXPORT CartesianPoint2D
{
public:

    //! Constructor
    CartesianPoint2D();


    //! Set x value
    void setX(const qreal &qrX);

   // ETC ETC ETC
};

} // namespace Calculus

///////////////////////////////////////////////////////////////////////////////
// RELATED NON-MEMBER OPERATORS                                              //
///////////////////////////////////////////////////////////////////////////////

//! Addition operator
Calculus::CartesianPoint2D operator +(const Calculus::CartesianPoint2D &xAPoint, const Calculus::CartesianPoint2D &xBPoint);

//! Subtraction operator
Calculus::CartesianPoint2D operator -(const Calculus::CartesianPoint2D &xAPoint, const Calculus::CartesianPoint2D &xBPoint);

// And so on...

#endif // POINT2D_H

When I use this library, class methods works well. But when I want to use an operator, I got the undefined reference error, for example:

path\sources\testcalculus.cpp:273: error: undefined reference to `operator+(Calculus::CartesianPoint2D const&, Calculus::CartesianPoint2D const&)'

What I must do to export also the overloaded operators and use them?

Thanks for your replies.

Answer 1

You have to use CALCULUSSHARED_EXPORT in your free functions (the operators in this case) too. This (I think) is true only to Windows.