LinuxQuestions.org - fltk error

Hello,
I'm having troubles using FLTK.

I found following code snapshot in some fltk tutorial:

Code:

#include <FL/Fl.H>

#include <FL/Fl_Window.H>

#include <FL/Fl_Button.H>

using namespace std;



//--------------------------------------------

void but_cb( Fl_Widget* o, void*  ) {

  Fl_Button* b=(Fl_Button*)o;

  b->label("Good job"); //redraw not necessary

 

  b->resize(10,150,140,30); //redraw needed

  b->redraw();

}



//-------------------------------------------- 

int main() {



    Fl_Window win( 300,200,"Testing" );

    win.begin();

      Fl_Button but( 10, 150, 70, 30, "Click me" );

    win.end();

    but.callback( but_cb );

    win.show();

    return Fl::run();

}

If I try to run this we eclipse, I'm getting following error:

Code:

11:58:45 **** Incremental Build of configuration Debug for project fltk ****

make all 

Building target: fltk

Invoking: Cross G++ Linker

g++  -o "fltk"  ./src/fltk.o  

../src/fltk.cpp:9: error: undefined reference to 'Fl_Widget::label(char const*)'

../src/fltk.cpp:12: error: undefined reference to 'Fl_Widget::redraw()'

../src/fltk.cpp:18: error: undefined reference to 'Fl_Window::Fl_Window(int, int, char const*)'

../src/fltk.cpp:19: error: undefined reference to 'Fl_Group::begin()'

../src/fltk.cpp:20: error: undefined reference to 'Fl_Button::Fl_Button(int, int, int, int, char const*)'

../src/fltk.cpp:21: error: undefined reference to 'Fl_Group::end()'

../src/fltk.cpp:23: error: undefined reference to 'Fl_Window::show()'

../src/fltk.cpp:24: error: undefined reference to 'Fl::run()'

../src/fltk.cpp:24: error: undefined reference to 'Fl_Window::~Fl_Window()'

../src/fltk.cpp:24: error: undefined reference to 'Fl_Window::~Fl_Window()'

/usr/local/include/FL/Fl_Button.H:75: error: undefined reference to 'vtable for Fl_Button'

/usr/local/include/FL/Fl_Button.H:75: error: undefined reference to 'Fl_Widget::~Fl_Widget()'

collect2: ld gab 1 als Ende-Status zurück

make: *** [fltk] Fehler 1



11:58:45 Build Finished (took 115ms)

I'm facing the same problem in a different project that uses fltk with qtcreator. I'm using Ubuntu 12.04 64bit running on a i5 notebook (acer 4820tg).

Thank you