Thread: Linker errors with Visual C++

I am using Visual C++ .NET 2003 and included some header files that I wrote for an earlier project. I will be using these header files in several future projects, so instead of adding a copy to each project, I added the path of the header files to the "Additional Include Directories" under Project Properties (C/C++ | General).

When I try to use the classes in the header files, for example one class is called MyVector, I get the following error:

nofb error LNK2019: unresolved external symbol "public: __thiscall MyVector::~MyVector(void)" (??1MyVector@@QAE@XZ) referenced in function "public: __thiscall Scene::Scene(void)" (??0Scene@@QAE@XZ)

But I noticed that this error only happens for functions that are defined in MyVector.cpp and not for functions that are defined in MyVector.h (such as simple "set" and "get" functions). I've spent all night playing with the settings and searching MSDN -- does anyone have any suggestions? Thanks!!


Here is an excerpt of my code if that helps...

Code:

// ====== Scene.h======

#ifndef SCENE_H_
#define SCENE_H_

#include <MyVector.h>

class Scene {

public:
	Scene();
	~Scene();
private:
	MyVector *points;
	int numPoints;

};

#endif

// ====== Scene.cpp ======

#include "Scene.h"

Scene::Scene() {

	numPoints = 14 * 3;

	// The following functions yield linker errors (LNK2019)
	points = new MyVector[numPoints];
	points[0].normalize();

	// The following functions do not yield linker errors
	points[0].setElement(0,2.0f);  // test build errors
	float i = points[0].getElement(0);
	int j = points[0].getLength();

} // end default constructor

Scene::~Scene() {

	delete [] points;  // Yields linker errors

} // end deconstructor

// ====== MyVector.h ======

#ifndef MYVECTOR_H_
#define MYVECTOR_H_

class MyVector {

public:
	MyVector();    // Implemented in MyVector.cpp
	~MyVector();  // Implemented in MyVector.cpp
	void normalize(); // Implemented in MyVector.cpp

	int getLength() { return length; }
	float getElement(int i) { return v[i]; }
	void setElement (int i, float c) { v[i] = c; }

private:

	float *v;
	int length;

};

#endif

You must first add the file to your project through the project menu -> add existing item. Then the compiler can compile the .CPP file and generate the .obj file the linker needs.

You have not shown us what is in MyVector.Cpp... Are you certain you have the MyVector destructor function coded there? You have told the compiler (in the MyVector.H file) that you are making your own destructor for the MyVector class. If you do not have this function defined in MyVector.Cpp then the class MyVector cannot be completely built and could be the cause of this error.

Yes, I have defined all the other functions (destructor, constructor) in MyVector.cpp. I've used MyVector in another project where the files were included in the project as velius described, but I thought there was a way to do it without adding all the files to the project. (Or else some of my projects are going to have a ton of files in them!)

I didn't think that the contents of MyVector.cpp were relavent to the question, but here is a portion of the class:

Code:

#include <cmath>
using std::sqrt;

#include "MyVector.h"
#include "VectorErr.h"

MyVector::MyVector() {

	length = 3;
	v = new float[length];
	for (int i = 0; i < length; i++) {
		v[i] = 0;
	} // end for

} // end default constructor


MyVector::~MyVector() {

  delete [] v;

} // end deconstructor


void MyVector::normalize() {

	MyVector *original = new MyVector(length);
	(*original) = (*this);
	float denom = 0;
	for (int i = 0; i < length; i++) {
		for (int j = 0; j < length; j++) {
			denom += original->getElement(j) * original->getElement(j);
		} // end for
		v[i] = original->getElement(i) / sqrt(denom);
		denom = 0;
	} // end for
  delete original;

} // end normalize