Ad:

C++ Discussion Thread
Unsolved
Views: 15753

Mar 19th, 2005

C++ Beginner - #include recursion problem

Expand Post »

I am new to C++ and cant get my program to compile because of #include recursion.

I have 3 classes A, B, C.

A includes B.h and C.h
B includes A.h
C includes A.h and B.h

They include each other because they either need to send messages between themselves.

No inheritance is involved.

I've tried using:
#ifndef
#define
.........
#endif
but because A and B are included twice they dont get included the second time.

Any ideas for a C++ beginner who's spent the last 2 days trying to botch something togeather?

Thanks,
James

Similar Threads

j.kelly

Reputation Points: 11

Solved Threads: 0

Newbie Poster

Offline

10 posts
since Mar 2005

Permalink

Mar 19th, 2005

Re: C++ Beginner - #include recursion problem

Can you give an example of how your headers look instead of just which includes the other?

Narue

Administrator

Reputation Points: 6442

Solved Threads: 1393

Bad Cop

Offline

11,807 posts
since Sep 2004

Permalink

Mar 19th, 2005

Re: C++ Beginner - #include recursion problem

As they stand they just recur:

#include "Lift.h"
#include "Control.h"
class Floor
{
public:
Floor(void);
~Floor(void);
private:
Control control;//to send requests
};

#include "Floor.h"
#include "Lift.h"
class Control
{
public:
Control();
~Control(void);
private:
Floor floor;//to update floor display
Lift lift;//to tell lift what to do
};

#include "Control.h"
class Lift
{
public:
Lift();
~Lift(void);
private:
Control control;//to send requests
};

j.kelly

Reputation Points: 11

Solved Threads: 0

Newbie Poster

Offline

10 posts
since Mar 2005

Permalink

Mar 19th, 2005

Re: C++ Beginner - #include recursion problem

If you want your classes to use each other, you pretty much need to do something like this using forward declarations and pointers (preferably smart pointers as they make your life easier):

C++ Syntax (Toggle Plain Text)
#ifndef FLOOR_H
#define FLOOR_H
 
#include <memory>
 
class Control;
 
class Floor
{
public:
  Floor(void);
  ~Floor(void);
private:
  std::auto_ptr<Control> control;//to send requests
};
 
#endif
#ifndef FLOOR_H
#define FLOOR_H

#include <memory>

class Control;

class Floor
{
public:
  Floor(void);
  ~Floor(void);
private:
  std::auto_ptr<Control> control;//to send requests
};

#endif

C++ Syntax (Toggle Plain Text)
#ifndef CONTROL_H
#define CONTROL_H
 
#include <memory>
 
class Floor;
class Lift;
 
class Control
{
public:
  Control();
  ~Control(void);
private:
  std::auto_ptr<Floor> floor;//to update floor display
  std::auto_ptr<Lift> lift;//to tell lift what to do
};
 
#endif
#ifndef CONTROL_H
#define CONTROL_H

#include <memory>

class Floor;
class Lift;

class Control
{
public:
  Control();
  ~Control(void);
private:
  std::auto_ptr<Floor> floor;//to update floor display
  std::auto_ptr<Lift> lift;//to tell lift what to do
};

#endif

C++ Syntax (Toggle Plain Text)
#ifndef LIFT_H
#define LIFT_H
 
#include <memory>
 
class Control;
 
class Lift
{
public:
  Lift();
  ~Lift(void);
private:
  std::auto_ptr<Control> control;//to send requests
};
 
#endif
#ifndef LIFT_H
#define LIFT_H

#include <memory>

class Control;

class Lift
{
public:
  Lift();
  ~Lift(void);
private:
  std::auto_ptr<Control> control;//to send requests
};

#endif

If you don't want to do that, you would be better off restructuring the classes so that they don't depend on each other:

C++ Syntax (Toggle Plain Text)
class Floor
{
public:
  Floor();
  ~Floor();
};
 
class Lift
{
public:
  Lift();
  ~Lift();
private:
  Floor floor[20]; // 20 story building
};
 
class Control
{
public:
  Control();
  ~Control();
private:
  Lift lift;
};
class Floor
{
public:
  Floor();
  ~Floor();
};

class Lift
{
public:
  Lift();
  ~Lift();
private:
  Floor floor[20]; // 20 story building
};

class Control
{
public:
  Control();
  ~Control();
private:
  Lift lift;
};

Control manipulates Lift through the Lift public interface and Lift manipulates the array of Floor through the Floor public interface. Any messaging is done that way. Of course, I don't know how your design is set up, so this suggestion may not work without significant changes.

Narue

Administrator

Reputation Points: 6442

Solved Threads: 1393

Bad Cop

Offline

11,807 posts
since Sep 2004

Permalink

Mar 19th, 2005

Re: C++ Beginner - #include recursion problem

Thanks for your help. That was really giving me a headache

James

j.kelly

Reputation Points: 11

Solved Threads: 0

Newbie Poster

Offline

10 posts
since Mar 2005

Permalink

May 18th, 2010

-3

Re: C++ Beginner - #include recursion problem

write a program which input a series of chracters until the user input .

by useing th recursive function??

can any one help

faaano

Reputation Points: 9

Solved Threads: 0

Newbie Poster

Offline

1 posts
since May 2010

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in C++ Forum Timeline: Require assistance

Next Thread in C++ Forum Timeline: hi,

DaniWeb Message

Cancel Changes

User Name
Password