Any solution to class redefinition

[boon kian]

Hi Anyone have a solution for class redefinition ?? I have a based class and 2 derived class. When i try to write a main function using both the derived class i have a class redefinition problem. Can anyone guide me on how to solve the prob ?? Thanx a lot !!! bk

[Anonymous]

Its not very clear what you mean, maybe you can give an example of what you are trying to do?

[boon kian]

eg: base class : class Employee { } derived class 1: class Temp:public Employee { } derived class 2: class Perm:public Employee { } main: #include "Perm.h" #include "Temp.h" <- this is where the redefinition occur due to 2 copy of "Employee.h" void main (void) { Temp a; Perm b; ...... } so beside changing the structure any solution to solve this prob ?? thanx a lot !! bk

[Jorgen Sigvardsson]

You need to protect the header file from multiple inclusions. A portable way is to do something like this:

#ifndef __FILE_H__
#define __FILE_H__

// Header file contents here

#endif // __FILE_H__

If you are not worried about portability and is using VS.NET, you can write something like this:

#pragma once
// Header file contents here

-- Shine, enlighten me - shine Shine, awaken me - shine Shine for all your suffering - shine

[Jorgen Sigvardsson]

Oh yeah, i forgot to mention that the define at the top of each header file should be unique for each header file. I usually use this pattern: If the file is called file.h, the define symbol becomes __FILE_H__ So, if I had Employee.h, I'd define the symbol as __EMPLOYEE_H__ :) -- Shine, enlighten me - shine Shine, awaken me - shine Shine for all your suffering - shine

[Stephane Rodriguez]

#pragma once huh?

[Jorgen Sigvardsson]

It automatically protects header files. A VS.NET extension which IMHO should be incorporated into C/C++. Idiot proof protection! :-D -- Shine, enlighten me - shine Shine, awaken me - shine Shine for all your suffering - shine

[Stephane Rodriguez]

me leaving the class room looking down my shoes. ;) [edit]#pragma once is not a VS.NET extension.[/edit]

[Jorgen Sigvardsson]

.S.Rod. wrote: [edit]#pragma once is not a VS.NET extension.[/edit] Did it appear earlier? I assumed it was first included in VS.NET because VS.NET was the first environment where I noticed that the wizards generate code containing #pragma once. Speaking of extensions, do you know by any chance if you can force folding points in C++ source files using some [un]documented trick? #region is what I want, but that seems to be a C# only feature. -- Shine, enlighten me - shine Shine, awaken me - shine Shine for all your suffering - shine

[Stephane Rodriguez]

Jörgen Sigvardsson wrote: Did it appear earlier? I assumed it was first included in VS.NET because VS.NET was the first environment where I noticed that the wizards generate code containing #pragma once. As far as I can tell it was already available with MSDEV 97. Jörgen Sigvardsson wrote: Speaking of extensions, do you know by any chance if you can force folding points in C++ source files using some [un]documented trick? #region is what I want, but that seems to be a C# only feature. There is no way to force outlining. But the context menu shows a way to play with outlines regardless of the language you are using (they are saved in the .suo file, like bookmarks and other stuff). More info here[^].

[Jorgen Sigvardsson]

.S.Rod. wrote: But the context menu shows a way to play with outlines regardless of the language you are using (they are saved in the .suo file, like bookmarks and other stuff). Yeah, I knew about that one. However, the .suo file is nothing I want to keep in CVS. The main reason I wanted to add the regions was to promote readability (hiding all the private stuff as much as possible which is of no interest anyway for the user of the class) and have it inlined in the code. Oh well, I guess I can't have everything. :) -- Shine, enlighten me - shine Shine, awaken me - shine Shine for all your suffering - shine

[boon kian]

Hi , Really thanx a lot for the help !!! bk

[Reservoir Dog]

It's not really a VS.NET extension coz i've used #pragma once in VC++ 6 also. Though not sure if it was present in earlier versions too or not. And you will know my name is the Lord when I lay my vengeance upon thee.