Already defined .obj problem.

Question

0.00/5 (No votes)

See more:

Hi friend,
I have facing the problem of "Already defined .obj". My console application consist of:
Lib.cpp, Lib.h, Pwrcom.h and global.cpp files. I have been included Pwrcom.h header in Lib.ccp and global.cpp files and also included Lib.h header in the global.ccp as well.

For Example:
Lib.cpp file
#include "Pwrcom.h"
#include "Lib.h"
-----------
---------

global.cpp file
#include "Pwrcom.h"
#include "Lib.h"
--------------------
-----------------

This Pwrcom.h consist of all global variable declaration. After I refered different forum and technical site, I come know that, Pwrcom.h used several times.. If I have remove "pwrcom.h" header file from global.cpp or else from Lib.cpp, compiler give out error report. Because those global variable has been used both the files "Global.cpp" and "Lib.cpp".
Kindly help me to fix this problem.

Thanks and Regards,
S.Shanmuga Raja

Posted 21-Mar-13 23:50pm

shanmugarajaa

Add a Solution

Comments

Richard MacCutchan 22-Mar-13 7:38am

You should look at your design. The use of global variables is generally unnecessary and should be avoided. you have fallen into the first trap that this design pattern may cause.

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Leo Chapiro · Answer 1 · 2013-03-22T00:18:00

Solution 1

Try to use following statement in every header file you write to be sure including the header file only once:

C++

#pragma once

This is better as like former:

C++

#ifndef _BLAH_
#define _BLAH_

#endif // _BLAH_

Posted 22-Mar-13 0:18am

Leo Chapiro

Updated 22-Mar-13 0:20am

v2

Comments

shanmugarajaa 22-Mar-13 6:44am

Hi,
I did the same what you are cite above.

Lib.ccp file
pragma once
#include "pwrcom.h"
#include "Lib.h"

Global.cpp
pragma once
#include "pwrcom.h"
#include "Lib.h"

But still i getting error..

Maxim Kartavenkov 22-Mar-13 8:13am

#pragma once - should be in .h file - had you seen example in my solution?

Maxim Kartavenkov · Answer 2 · 2013-03-22T00:19:00

You should declare variables in .h files but initialize them in .cpp file.
Otherwise you include header 2 times and then it is initialize 2 times.
Note: do not forget to use #pragma once or via definition avoid doublbe declaration.

C++

//example: .h

#pragma once
// declare variable so compiler will know 
// that it will be initialized sometehre
extern int g_variable;

//example .cpp
// initialize variable
// we should initialize it as you will linker error unresolved symbol as 
// variable marked as extern
int g_variable = 0;

// in any other files there you include header you will not get the linker error

Maxim.