unresolved external symbol, C++

Question

I'm getting an error when trying to build a project regarding unresolved external symbols, however I can't find out where my issue lies, anyone got any ideas? thanks

Tball.cpp

#include "Tball.h"
#include <Windows.h>
using namespace std;



Tball::Tball(){

 Position = TVector(70,0,70);
 Verlocity = TVector(1,0,1);

}

Tball.h

#ifndef Tball_h
#define Tball_h

#include <iostream>
#include "mathex.h"
#include "tvector.h"


class Tball
{

public:

static TVector Position;
static TVector Verlocity;


Tball();
static void DrawBall(float x, float y, float z);
static TVector MoveBall();
static void init();
static int loadbitmap(char *filename);
static void SurfaceNormalVector();
static double Tball::collision();
static void Tball::pointz();



};


#endif

Error:

1>------ Build started: Project: Breakout Complete, Configuration: Debug Win32 ------
1>  Tball.cpp
1>  Generating Code...
1>g:\work\second year\c++ breakout complete\breakout complete\tball.cpp(59): warning     C4715: 'Tball::MoveBall' : not all control paths return a value
1>  Skipping... (no relevant changes detected)
1>  Tvector.cpp
1>  TdisplayImp.cpp
1>  TBricks.cpp
1>Tball.obj : error LNK2001: unresolved external symbol "public: static class     TVector     Tball::Verlocity" (?Verlocity@Tball@@2VTVector@@A)
1>Tball.obj : error LNK2001: unresolved external symbol "public: static class     TVector     Tball::Position" (?Position@Tball@@2VTVector@@A)
1>G:\Work\Second year\C++ Breakout Complete\Debug\Breakout Complete.exe : fatal error     LNK1120: 2 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Nothing I've tried seems to work for me.

Answer 1

Put this into your cpp:

TVector Tball::Position(/* contructor params */);
TVector Tball::Verlocity(/* contructor params */);

This make the "space" for these member static variables.