How to make classes in NACHOS (C++)

Question

I am trying to implement a player class, so I created two files in my threads folder, player.cc and player.h

player.h goes like this :

#ifndef PLAYER_H
#define PLAYER_H
#include "utility.h"

class Player()
{
  public:
   //getPlayerID();
};

#endif

then player.cc goes like

#include "player.h"

class Player()
{
  string playerID;
  int timeCycle;
}

Then in my main.cc and threadtest.cc , I add in #include player.h and then I start to errors and it fails to compile. I am new to nachos and a little bit unfamiliar with c++, so I am confused as to how to resolve this problem. Nachos does not provide a solution through the compiler either.

When I type gmake, it says two things for errors. 1. parse error before '(' in player.h (referring to Player()) 2. * [main.o] Error 1

IIRC, NachOS is an academic operating system (which means this is probably homework). What are you trying to do? — Etienne de Martel, Sep 26 '11 at 01:27
well it supports c or c++ to some extent as a lot of these files are .cc //On a second note, it might not implement a full C++ runtime, but it is capable of running c++ files and I just need to figure how to get mine to work ^^ — krikara, Sep 26 '11 at 01:28

Ben Voigt · Accepted Answer · 2012-06-26T14:04:53.523

Let's go through line-by-line:

#ifndef PLAYER_H
#define PLAYER_H
#include "utility.h"

So far so good, you might check if your compiler supports #pragma once, but the macro will work perfectly fine.

class Player()

() aren't allowed in a class name, take them off

{
  public:
   //getPlayerID();
};

#endif

The rest of the header file is ok. Let's look at the implementation file:

#include "player.h"

Perfect. Putting a class in a header is the best way to make sure you only have one definition used in your whole program.

class Player()

Parentheses aren't allowed, but here you have a bigger problem. You already have a class with that name. Let the header provide the class definition, the implementation file just needs to provide the non-inline member functions (and any helper code).

{
  string playerID;
  int timeCycle;
}

Here's a complete corrected version:

#if !defined(PLAYER_H)
#define PLAYER_H

#include <string>
#include "utility.h"

class Player
{
     std::string player_id;
     int time_cycle;

public:
     // this is how you make a constructor, the parenthesis belong here, not on the class name
     Player(std::string id, int time);

     std::string getPlayerId() const;
};

#endif /* !defined(PLAYER_H) */

and implementation file

#include "player.h"

// and this is how you write a non-inline constructor
Player::Player(std::string id, int time)
    : player_id(id)
    , time_cycle(time)
{}

std::string Player::getPlayerId() const
{
    return player_id;
}

All of these problems are really basic C++ stuff, nothing to do with NachOS.

This works great and it compiles now. But now let's say I wanted to initialize a player with both a playerID and timeCycle. I originally put player() because I wanted to change it to player(string playerID, int timeCycle) . From what I know, getters and setters are done differently in c++ — krikara, Sep 26 '11 at 01:43
@krikara: The constructor declaration goes INSIDE the class. I'll edit with an example. — Ben Voigt, Sep 26 '11 at 01:52
#include should be #include . Otherwise you include the C file. — markus_p, Jun 26 '12 at 08:28

score 1 · Answer 2 · edited Dec 03 '12 at 03:13

1

Did you modify the Makefile.common in the root nachos directory? I think you should add some value to THREAD_H, THREAD_O and THREAD_C.

edited Dec 03 '12 at 03:13

David G

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answered Dec 03 '12 at 02:54

Liu Shuo

11
3

How to make classes in NACHOS (C++)

2 Answers2