LNK2019 & LNK2001 Errors

[adwatson]

I am currently programming the checkers game Fox and Hound with FLTK for a project. When I compile, I get 69 linker errors. Any help with these errors would be appreciated. The code in question is as follows:

#include "GUI.h"
#include "fltk.h"
#include "std_lib_facilities.h"
#include "Graph.h"
#include <stdlib.h>

using namespace Graph_lib;

using namespace std;

//Create a new kind of button 
class Button2 : public Button {
public:
	Address p;
	Point pt;
	Button2(Point xy, int ww, int hh, const string& s, Callback cb)
		:Button(xy,ww,hh,s,cb),pt(xy.x,xy.y){}
	virtual void attach(Window& win)
	{
		pw = new Fl_Button(loc.x, loc.y, width, height, label.c_str());
		pw->callback(reinterpret_cast<Fl_Callback*>(do_it), this); // pass the window
		own = &win;
		p = &win;
	}
};

struct Checker
{
	bool WC;
	bool active;
	Point p;
	Circle inner;
	Circle outer;
	Checker(bool w_c, Point pt):WC(w_c),p(pt),inner(p,25),outer(p,48),active(true){}
};

//Class Main_window is a new kind of window where the game takes place
struct Main_window: Graph_lib::Window {

	
    
	Main_window(Point p, int w, int h, const string& title);
	
	Vector_ref<Rectangle> table;

	Vector_ref<Checker> checkers;
	
	Vector_ref< Vector_ref<Button2> > buttons;
	
	Vector_ref<Player> players;
	//Buttons used in the game
	private:

	Text* instruction;
		
	Button quit_button;
	
	Button start_button;
	
	Button help_button;
	
	Out_box move_box; //displays number of moves
	
	static void cb_quit(Address,Address pw);
	
	static void cb_click(Address,Address pw);
	
	static void cb_start(Address, Address pw);
	
	static void cb_help(Address, Address pw);
	
	static void refresh(bool endgame);
	
	void click(Address active_button);
	
	void quit();
	
	void start();
	
	void help();

};

int moves=0;
bool gameover=false;

//Initialize the main window
Main_window::Main_window(Point p, int w, int h, const string& title):Window(p,w,h,title),
quit_button(Point(x_max()-80,y_max()/2),70,20,"Quit",cb_quit),help_button(Point(x_max()-80,y_max()/2-60),70,20,"Help",cb_help),start_button(Point(x_max()-80,y_max()/2 -30),70,20,"Start",cb_start),
move_box(Point(600,50),70,20,"Number of Moves")
{	
	
	instruction = new Text(Point(20,550),"Instruction: You may move one square diagonally in any direction.");
	
	for (int i=0;i<8;i++)
	{
		for (int j=0;j<8;j++)
		{
			table.push_back(new Rectangle(Point(j*100,i*100),100,100));
			buttons[i].push_back(new Button2(Point(j*100,i*100),100,100,"",Main_window::cb_click));
			if ((j-i)%2==0)
			{
				table[table.size()-1].set_color(Color::white);
				table[table.size()-1].set_fill_color(Color::white);
		    }
			else
			{
				table[table.size()-1].set_color(Color::black);
				table[table.size()-1].set_fill_color(Color::black);		
			}
			attach(table[table.size()-1]);
			attach(buttons[i][j]);
		}
	}
	attach(quit_button);
	attach(start_button);
	attach(help_button);
	attach(move_box);
}

void Main_window::start()
	{ 
		refresh(gameover);
	}
void Main_window::cb_quit(Address, Address pw)
	{
		reference_to<Main_window>(pw).quit();
	}	

void Main_window::cb_start(Address, Address pw)
	{
		reference_to<Main_window>(pw).start();
	}	

void Main_window::cb_help(Address, Address pw)
	{
		reference_to<Main_window>(pw).help();
	}

void Main_window::cb_click(Address active_button, Address pw)
	{
	
		reference_to<Button2>(pw).hide();
		reference_to<Main_window>(reference_to<Button2>(pw).p).click(pw);
	
	}	

void Main_window::click(Address pw)
{
	int index=-1;
	int ind_x;
	int ind_y;
	for (int i=0; i<checkers.size(); i++)
			if(&checkers[i].WC == false && checkers[i].active==true)
				index=i;
	for (int i=0; i<8; i++)
	{
		for (int j=0; j<8; j++)
		{
			if (&buttons[i][j]==pw)
			{
				ind_y=50+(i*100);
				ind_x=50+(j*100);
			}
		}
	}
	if(index>=0)
	{
		detach(checkers[index].inner);
		detach(checkers[index].outer);
	}
	checkers.push_back(new Checker(false,Point(ind_x,ind_y)));
	checkers[checkers.size()-1].inner.set_style(Line_style(Line_style::solid,50));
	checkers[checkers.size()-1].inner.set_color(Color::white);
	checkers[checkers.size()-1].outer.set_style(Line_style(Line_style::solid,5));
	attach(checkers[checkers.size()-1].inner);
	attach(checkers[checkers.size()-1].outer);
	move_box.put(moves);
	moves++;
}	

void Main_window::help()
	{
		attach(*instruction);
		
	}
void Main_window::quit()
	{
		hide();
	}	
void Main_window::refresh(bool endgame) 
	{
	  if (endgame==1)
		  exit(0);
	  else
	  {
		Fl::wait();
		Fl::redraw();
		refresh(gameover);
	  }
	}

[anonymous23323124]

Hasve you linked all the static libraries corresponding to any libraries you are using? LNK2019 "undefined symbol ..." means you have used symbols (i.e. function, variable, etc. names) which are declared (probably in headers) but not implemented.

[adwatson]

To be honest I wouldn't know how to go about doing that. For the record here are some of the errors I am getting:

game.obj : error LNK2019: unresolved external symbol "public: void __thiscall Fl_Widget::show(void)" (?show@Fl_Widget@@QAEXXZ) referenced in function "public: virtual void __thiscall Graph_lib::Widget::show(void)" (?show@Widget@Graph_lib@@UAEXXZ)
GUI.obj : error LNK2001: unresolved external symbol "public: void __thiscall Fl_Widget::show(void)" (?show@Fl_Widget@@QAEXXZ)
Main_window.obj : error LNK2001: unresolved external symbol "public: void __thiscall Fl_Widget::show(void)" (?show@Fl_Widget@@QAEXXZ)
Graph.obj : error LNK2001: unresolved external symbol "int fl_font_" (?fl_font_@@3HA)
Main_window.obj : error LNK2001: unresolved external symbol "int fl_font_" (?fl_font_@@3HA)
Graph.obj : error LNK2001: unresolved external symbol "int fl_size_" (?fl_size_@@3HA)
Main_window.obj : error LNK2001: unresolved external symbol "int fl_size_" (?fl_size_@@3HA)
Main_window.obj : error LNK2019: unresolved external symbol "public: static void __cdecl Fl::redraw(void)" (?redraw@Fl@@SAXXZ) referenced in function "private: static void __cdecl Main_window::refresh(bool)" (?refresh@Main_window@@CAX_N@Z)
Main_window.obj : error LNK2019: unresolved external symbol "public: static int __cdecl Fl::wait(void)" (?wait@Fl@@SAHXZ) referenced in function "private: static void __cdecl Main_window::refresh(bool)" (?refresh@Main_window@@CAX_N@Z)

[anonymous23323124]

Well presumably you downloaded some library: FLTK presumably, although I've not actually heard of this library until now. It seems you found your way to the header files alright.

You should also be able to find some "*.lib" or "*.a" files in there, and you have to add them to your linker input list. I may be able to help you with doing this, but you'll have to tell me which IDE you are using.

[adwatson]

Never mind, I realized what you meant and added the correct .lib files to the linker additional dependencies in Visual Studio 2008. Thank you!

[anonymous23323124]

No problem. Glad to help!