Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Circular Definitions

Posted on 2000-04-12
2
Medium Priority
?
285 Views
Last Modified: 2013-11-20
I have a number of header files that are dependent on each other. For example, the defintion of object A contains a reference to the defintion of object B. And the defintion of object B contains a reference to the defintion of object A. Object A and B are in different files. I have tried to solve the problem by doing the following in the first file:

class B;
class A
{
B objectB;
}

And doing the following in the other file:
class A;
class B
{
A objectA;
}

But the problem is still not solved!!
What am I suppose to do to solve this problem?

Thank you.
0
Comment
Question by:Zainal062797
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 1

Accepted Solution

by:
MT_MU earned 150 total points
ID: 2709239
I'm not sure why, but if you change to ptr reference it will work.

class B;
class A
{
B* objectB;
}

And doing the following in the other file:
class A;
class B
{
A* objectA;
}

0
 
LVL 1

Expert Comment

by:tao_shaobin
ID: 2709405
The reasons why it works after we change them to pointers are:

B* objectB; is only a declaration.  It won't call anything, including construtors of B.  But B objectB; may call the construtor which may initialize some variables.  

In this case, it is impossible to declare circular declarations if both classes need to initialize some variables in their construtors.  Therefore, we need to prevent this to happen.  If not of all of them need initilization, then you can declare like this(suppose A needs not to initialize)

a.h

#include "B.h"  // only way
class A
{
  B  bobject;
  ....
{

b.h

class A;
class B
{
  A aObject;
  ....
}

Then, your program should work.

Help this helps,

tao_shaobin
0

Featured Post

Moving data to the cloud? Find out if you’re ready

Before moving to the cloud, it is important to carefully define your db needs, plan for the migration & understand prod. environment. This wp explains how to define what you need from a cloud provider, plan for the migration & what putting a cloud solution into practice entails.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction: Load and Save to file, Document-View interaction inside the SDI. Continuing from the second article about sudoku.   Open the project in visual studio. From the class view select CSudokuDoc and double click to open the header …
Introduction: Hints for the grid button.  Nested classes, templated collections.  Squash that darned bug! Continuing from the sixth article about sudoku.   Open the project in visual studio. First we will finish with the SUD_SETVALUE messa…
This video will show you how to get GIT to work in Eclipse.   It will walk you through how to install the EGit plugin in eclipse and how to checkout an existing repository.
Monitoring a network: how to monitor network services and why? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the philosophy behind service monitoring and why a handshake validation is critical in network monitoring. Software utilized …
Suggested Courses

721 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question