Undefined reference to Object::O

Main method:#include <iostream>#include <cstdlib>#include "SDL.h"#include "object.h"using namespace std;/*class Object{	int foo;	public:	Object(){		foo = 1024;	}};*/int main(int argc, char *argv[]){	cout <<"Initializing SDL." << endl;	int quit = 0;	SDL_Event event;	SDL_Surface *screen;	if(SDL_Init(SDL_INIT_VIDEO)< 0) {		cout <<"Could not initialize SDL:" << SDL_GetError() << endl;		SDL_Quit();		return 2;	} else {		cout << "SDL initialized.";	}	screen = SDL_SetVideoMode(800,600,0,SDL_SWSURFACE);	if(screen == NULL){		cout <<"Error creating surface:" << SDL_GetError() << endl;		SDL_Quit();		return 2;	}	Object ball;	while(!quit){		while(SDL_PollEvent(&event)){			switch(event.type){				case SDL_QUIT : quit = 1; break;				case SDLK_LEFT : break;				default : break;			}		}	}	SDL_Quit();	return 0;}Object.h:#ifndef OBJECT_H#define OBJECT_Husing namespace std;class Object{	public:	Object();	Object(long ID);	Object(long ID,int position[2]);	void setXVel(int velocity);	void setYVel(int velocity);	void setPos(int position[2]);	void updatePos();};#endifobject.cpp:#include "SDL.h"using namespace std;class Object{	int xvel,yvel;	int pos[2]; //(x,y) format - pos[0] = x, pos[1] = y	long ident;	public:	Object(){		xvel = yvel = 0;	}	Object(long ID){		ident = ID;		xvel = yvel = 0;	}	Object(long ID,int position[2]){		ident = ID;		setPos(position);		xvel = yvel = 0;	}	void setXVel(int vel){		xvel = vel;	}	void setYVel(int vel){		yvel = vel;	}	void updatePos(){		pos[0] += xvel;		pos[1] += yvel;	}	void setPos(int position[2]){		pos[0] = position[0];		pos[1] = position[1];	}	virtual ~Object();};