Undefined reference

[JavierSivack]

Hello,
I´m really a beginner on C++, I just started using it because I'm reading "Programming Game AI by Examples" book, but I have some problem compiling the examples. I wonder if some one can help me with this.
I have this error:

"Buckland_Chapter2-State Machines\WestWorldWithMessaging\MessageDispatcher.o:MessageDispatcher.cpp|| undefined reference to `CrudeTimer::Instance()'|"

#include "CrudeTimer.h"


CrudeTimer* CrudeTimer::Instance()
{
  static CrudeTimer instance;

  return &instance;
}

#ifndef CRUDETIMER_H
#define CRUDETIMER_H
//------------------------------------------------------------------------
//
//  Name:   CrudeTimer.h
//
//  Desc:   timer to measure time in seconds
//
//  Author: Mat Buckland 2002 ([e-mail])
//
//------------------------------------------------------------------------

//this library must be included
#pragma comment(lib, "winmm.lib")

#include <windows.h>



#define Clock CrudeTimer::Instance()

class CrudeTimer
{
private:

  //set to the time (in seconds) when class is instantiated
  double m_dStartTime;

  //set the start time
  CrudeTimer(){m_dStartTime = timeGetTime() * 0.001;}

  //copy ctor and assignment should be private
  CrudeTimer(const CrudeTimer&);
  CrudeTimer& operator=(const CrudeTimer&);

public:

  static CrudeTimer* Instance();

  //returns how much time has elapsed since the timer was started
  double GetCurrentTime(){return timeGetTime() * 0.001 - m_dStartTime;}

};







#endif

#include "MessageDispatcher.h"
#include "BaseGameEntity.h"
#include "Time/CrudeTimer.h"
#include "EntityManager.h"
#include "Locations.h"
#include "MessageTypes.h"
#include "EntityNames.h"

#include <iostream>
using std::cout;

using std::set;

#ifdef TEXTOUTPUT
#include <fstream>
extern std::ofstream os;
#define cout os
#endif



//------------------------------ Instance -------------------------------------

MessageDispatcher* MessageDispatcher::Instance()
{
  static MessageDispatcher instance;

  return &instance;
}


//----------------------------- Dispatch ---------------------------------
//
//  see description in header
//------------------------------------------------------------------------
void MessageDispatcher::Discharge(BaseGameEntity* pReceiver,
                                  const Telegram& telegram)
{
  if (!pReceiver->HandleMessage(telegram))
  {
    //telegram could not be handled
    cout << "Message not handled";
  }
}

//---------------------------- DispatchMessage ---------------------------
//
//  given a message, a receiver, a sender and any time delay , this function
//  routes the message to the correct agent (if no delay) or stores
//  in the message queue to be dispatched at the correct time
//------------------------------------------------------------------------
void MessageDispatcher::DispatchMessage(double  delay,
                                        int    sender,
                                        int    receiver,
                                        int    msg,
                                        void*  ExtraInfo)
{
  SetTextColor(BACKGROUND_RED|FOREGROUND_RED|FOREGROUND_GREEN|FOREGROUND_BLUE);

  //get pointers to the sender and receiver
  BaseGameEntity* pSender   = EntityMgr->GetEntityFromID(sender);
  BaseGameEntity* pReceiver = EntityMgr->GetEntityFromID(receiver);

  //make sure the receiver is valid
  if (pReceiver == NULL)
  {
    cout << "\nWarning! No Receiver with ID of " << receiver << " found";

    return;
  }
  GetCurrentTime;
  //create the telegram
  Telegram telegram(0, sender, receiver, msg, ExtraInfo);

  //if there is no delay, route telegram immediately
  if (delay <= 0.0f)
  {
    cout << "\nInstant telegram dispatched at time: " << Clock->GetCurrentTime()
         << " by " << GetNameOfEntity(pSender->ID()) << " for " << GetNameOfEntity(pReceiver->ID())
         << ". Msg is "<< MsgToStr(msg);

    //send the telegram to the recipient
    Discharge(pReceiver, telegram);
  }

  //else calculate the time when the telegram should be dispatched
  else
  {
    double CurrentTime = Clock->GetCurrentTime();

    telegram.DispatchTime = CurrentTime + delay;

    //and put it in the queue
    PriorityQ.insert(telegram);

    cout << "\nDelayed telegram from " << GetNameOfEntity(pSender->ID()) << " recorded at time "
            << Clock->GetCurrentTime() << " for " << GetNameOfEntity(pReceiver->ID())
            << ". Msg is "<< MsgToStr(msg);

  }
}


//---------------------- DispatchDelayedMessages -------------------------
//
//  This function dispatches any telegrams with a timestamp that has
//  expired. Any dispatched telegrams are removed from the queue
//------------------------------------------------------------------------
void MessageDispatcher::DispatchDelayedMessages()
{
  SetTextColor(BACKGROUND_RED|FOREGROUND_RED|FOREGROUND_GREEN|FOREGROUND_BLUE);

  //get current time
  double CurrentTime = Clock->GetCurrentTime();

  //now peek at the queue to see if any telegrams need dispatching.
  //remove all telegrams from the front of the queue that have gone
  //past their sell by date
  while( !PriorityQ.empty() &&
         (PriorityQ.begin()->DispatchTime < CurrentTime) &&
         (PriorityQ.begin()->DispatchTime > 0) )
  {
    //read the telegram from the front of the queue
    const Telegram& telegram = *PriorityQ.begin();

    //find the recipient
    BaseGameEntity* pReceiver = EntityMgr->GetEntityFromID(telegram.Receiver);

    cout << "\nQueued telegram ready for dispatch: Sent to "
         << GetNameOfEntity(pReceiver->ID()) << ". Msg is " << MsgToStr(telegram.Msg);

    //send the telegram to the recipient
    Discharge(pReceiver, telegram);

    //remove it from the queue
    PriorityQ.erase(PriorityQ.begin());
  }
}

I'm using Code:Block with GNU GCC compiler. the code of this examples can be found on http://www.jblearning.com/Catalog/9781556220784/student/.

Thank you in advance.
Javier.
PD: Sorry about my English writing skills-

[kbw]

You are missing a file that has the implementation of CrudeTimer, probably CrudeTimer.cpp.

But you can do without it. Add this code to CrudeTimer.h.

inline CrudeTimer* CrudeTimer::Instance()
{
    static CrudeTimer timer;
    return &timer;
}

[JavierSivack]

Thanks kbw, but the first code snippet is CrudeTimer.cpp.
I assume that maybe is some problem with the wrong compiler? Because I can't compile any of the examples, with different errors. Or maybe I'm setting paths and libs wrong way...

[kbw]

Sorry, I missed that.

You need to check you are linking with it.

[JavierSivack]

Thanks, I really don't know how to do that, on code::block I add the root commons directory at "Search Directories"->"Linker"
Maybe the problem is that the source is intend to be for VS8 ??

[JavierSivack]

Maybe related to this other error?

obj\Debug\VS8 projects\Buckland_Chapter2-State Machines\WestWorldWithMessaging\MessageDispatcher.o:MessageDispatcher.cpp:(.text$_ZN10CrudeTimer12GetTickCountEv[CrudeTimer::GetTickCount()]+0x7)||undefined reference to `timeGetTime@0'|

I assume that tis "timeGetTime" is from #include <windows.h>

[JavierSivack]

I Just Manage it! But I don't understand any way....
At the MessageDispatcher.cpp every time it use Clock->GetCurrentTime() I change it to only this GetCurrentTime() and it works like a charm...
If some one want to explain me why it is I will appreciate it.

[kbw]

I don't understand why that works.