so I made a "main.h" and placed all those variables and function definitions in that.
Hopefully you meant "declarations." Don't put the definitions in a header!
#ifndef not working
Please post the revised code, and the error messages. I have not tried to compile your code, but something like that should work. For example, I didn't include the header guards in globals.h, you'll still need them. And as mentioned, if you're declaring a global instance of Graphics, you'll need to include graphics.h in globals.h.I tried that. I got lots of errors.
I'd second Buckeye's suggestion to remove all references to your functions and headers from stdafx.h. Unless you really know what you're doing, it is probably best to reserve stdafx.h for referencing external headers (like Windows.h) that really are used everywhere. In fact, it might be best to leave stdafx.h empty for the time being until you've figured out this problem first.
Author
I'd second Buckeye's suggestion to remove all references to your functions and headers from stdafx.h. Unless you really know what you're doing, it is probably best to reserve stdafx.h for referencing external headers (like Windows.h) that really are used everywhere. In fact, it might be best to leave stdafx.h empty for the time being until you've figured out this problem first.
The problem with doing that is I have dependencies that require a certain order of "inclusion". I can't depend on the compiler to look through the header files in the right order.
Please post the revised code
I have a lot of code to look at now. I could post it if you think it will help, but here is the gist of what I have done:
--I have a header file for each .cpp file
--Each header file is "#included" is the stdafx.h file (in the order I need them)
--Each header file has:
#ifndef (header name in all caps such as GLOBALS_H)
#define (header name in all caps such as GLOBALS_H)
..... all the stuff needed in the header file.......
#endif
--Each .cpp file "#includes" the stdafx.h file
--stdafx.h has the same #ifndef / #define / #endif stuff as all the other headers
Here is the errors I'm getting when I do this:
Error 1 error LNK2005: "float SCREEN_WIDTH" (?SCREEN_WIDTH@@3MA) already defined in globals.obj C:\Empty DX11 Project1\Grapgics.obj Empty DX11 Project1
Error 2 error LNK2005: "float SCREEN_HEIGHT" (?SCREEN_HEIGHT@@3MA) already defined in globals.obj C:\Empty DX11 Project1\Grapgics.obj Empty DX11 Project1
Error 3 error LNK2005: "struct GRAPHICS Graphics" (?Graphics@@3UGRAPHICS@@A) already defined in globals.obj C:\Empty DX11 Project1\Grapgics.obj Empty DX11 Project1
Error 4 error LNK2005: "float SCREEN_WIDTH" (?SCREEN_WIDTH@@3MA) already defined in globals.obj C:\Empty DX11 Project1\LargeMath.obj Empty DX11 Project1
Error 5 error LNK2005: "float SCREEN_HEIGHT" (?SCREEN_HEIGHT@@3MA) already defined in globals.obj C:\Empty DX11 Project1\LargeMath.obj Empty DX11 Project1
Error 6 error LNK2005: "struct GRAPHICS Graphics" (?Graphics@@3UGRAPHICS@@A) already defined in globals.obj C:\Empty DX11 Project1\LargeMath.obj Empty DX11 Project1
Error 7 error LNK2005: "float SCREEN_WIDTH" (?SCREEN_WIDTH@@3MA) already defined in globals.obj C:\Empty DX11 Project1\main.obj Empty DX11 Project1
Error 8 error LNK2005: "float SCREEN_HEIGHT" (?SCREEN_HEIGHT@@3MA) already defined in globals.obj C:\Empty DX11 Project1\main.obj Empty DX11 Project1
Error 9 error LNK2005: "struct GRAPHICS Graphics" (?Graphics@@3UGRAPHICS@@A) already defined in globals.obj C:\Empty DX11 Project1\main.obj Empty DX11 Project1
Error 10 error LNK2005: "float SCREEN_WIDTH" (?SCREEN_WIDTH@@3MA) already defined in globals.obj C:\Empty DX11 Project1\MeshObject.obj Empty DX11 Project1
Error 11 error LNK2005: "float SCREEN_HEIGHT" (?SCREEN_HEIGHT@@3MA) already defined in globals.obj C:\Empty DX11 Project1\MeshObject.obj Empty DX11 Project1
Error 12 error LNK2005: "struct GRAPHICS Graphics" (?Graphics@@3UGRAPHICS@@A) already defined in globals.obj C:\Empty DX11 Project1\MeshObject.obj Empty DX11 Project1
Error 13 error LNK2005: "float SCREEN_WIDTH" (?SCREEN_WIDTH@@3MA) already defined in globals.obj C:\Empty DX11 Project1\Text.obj Empty DX11 Project1
Error 14 error LNK2005: "float SCREEN_HEIGHT" (?SCREEN_HEIGHT@@3MA) already defined in globals.obj C:\Empty DX11 Project1\Text.obj Empty DX11 Project1
Error 15 error LNK2005: "struct GRAPHICS Graphics" (?Graphics@@3UGRAPHICS@@A) already defined in globals.obj C:\Empty DX11 Project1\Text.obj Empty DX11 Project1
Error 16 error LNK1169: one or more multiply defined symbols found C:\Empty DX11 Project1\Release\DX11Test.exe 1 1 Empty DX11 Project1
17 IntelliSense: command-line error: invalid macro definition: /MDd c:\Empty DX11 Project1\Text.cpp 1 1 Empty DX11 Project1
The /MDd error only shows up when the other errors do. When I change it to the way I *was* doing it, that error doesn't occur.....
From the errors you listed, it appears you're still defining (not declaring but defining) globals in header files. Either that, or you're defining the same global in more than one cpp file.
That is, it appears that some header file has something like:
float SCREEN_WIDTH; // not in a header file!instead of
extern float SCREEN_WIDTH;Check for that problem, and also ensure that float SCREEN_WIDTH; appears in only one cpp file.
Each header file is "#included" is the stdafx.h file (in the order I need them)
Two things:
First: if header files other than system-related files (sdkver, windows, etc.) have to be in a particular order, that's an indication of a potential problem. Can you describe why the order of header files makes a difference?
Second: As mentioned, stdafx.h should be reserved for information that all (or most) cpp files need - things like windows.x, etc. Including all project header files in stdafx.h isn't recommended. Cpp files should have include only those header files that are needed.
You may not want to try it at this point, but the #ifndef HEADER/#define HEADER/#endif can be replaced with a single #pragma once at the very top of the file.
EDIT: with regard to structs: [EDIT: deleted some incorrect terminology about structs - apologies]
Author
I need some variables as global variables so that they may be used in multiple .cpp files. Exactly how should I do this? Should I use:
extern float WhateverVariable;
in a header file?
extern float WhateverVariable;
in a header file?
I'd recommend starting simple, you've a lot going on in your current program, so it is difficult to diagnose what is happening. Can you create a new project to try a simpler program - two source files and a header.
The following should work:
globals.h
The following should work:
globals.h
#ifndef GLOBALS_H
#define GLOBALS_H
extern float SCREEN_WIDTH;
extern float SCREEN_HEIGHT;
#endif
#include "globals.h"
float SCREEN_WIDTH = 13.0f;
float SCREEN_HEIGHT = 42.0f;
#include "globals.h"
#include <iostream>
int main() {
std::cout << "Screen: " << SCREEN_WIDTH << "x" << SCREEN_HEIGHT << std::endl;
}
Author
That gives me:
Error 1 error LNK2005: "float SCREEN_WIDTH" (?SCREEN_WIDTH@@3MA) already defined in globals.obj C:\Empty DX11 Project1\main.obj Empty DX11 Project1
Error 2 error LNK2005: "float SCREEN_HEIGHT" (?SCREEN_HEIGHT@@3MA) already defined in globals.obj C:\Empty DX11 Project1\main.obj Empty DX11 Project1
Error 3 error LNK1169: one or more multiply defined symbols found C:\Empty DX11 Project1\Release\DX11Test.exe Empty DX11 Project1
I tried playing with PCH, but all I got were errors.
The main thing is that I want to have *some* global variables. These would be common-use variables like the graphics interface. I want to do this so I don't have to send a reference each time some part of the program needs a pointer to the device......
Author
GOT IT!
in stdafx.h I (extern) declare:
extern GRAPHICS *GE;//my graphics interface pointer
and in main.h I actually declare it:
GRAPHICS *GE;
this gives me "global" availability of the variable.................
GOT IT!
in stdafx.h I (extern) declare:
extern GRAPHICS *GE;//my graphics interface pointer
and in main.h I actually declare it:
GRAPHICS *GE;
this gives me "global" availability of the variable.................
Actually, you don't got it. 
First: GRAPHICS *GE both declares GE AND defines it.
Read this --> Don't define variables in header files. If you must have a global variable, define it in a CPP file.
Also, if you're going to define a global variable, it's good practice to initialize it. I.e., GRAPHICS *GE = NULL;
I WANT TO CORRECT THIS!
Just trying to help out, Hawkblood. You posted this thread, looking to solve a problem, but you're ignoring the solution.
Works for me:
user@host:~/help$ for file in globals.{h,cpp} main.cpp; do echo "${file}:"; cat $file; done
globals.h:
#ifndef GLOBALS_H
#define GLOBALS_H
extern float SCREEN_WIDTH;
extern float SCREEN_HEIGHT;
#endif
globals.cpp:
#include "globals.h"
float SCREEN_WIDTH = 13.0f;
float SCREEN_HEIGHT = 42.0f;
main.cpp:
#include "globals.h"
#include <iostream>
int main() {
std::cout << "Screen: " << SCREEN_WIDTH << "x" << SCREEN_HEIGHT << std::endl;
}
user@host:~/help$ g++ main.cpp globals.cpp -o help
user@host:~/help$ ./help
Screen: 13x42
GOT IT!
...
and in main.h I actually declare it:
GRAPHICS *GE;
This will appear to work fine if main.h is only #included into a single source file (i.e. main.cpp). Remember #include is glorified copy and paste - the compiler will see a file that ends with the contents of main.cpp with the contents of every included file at the top (assuming the convention where #include occurs at the top of the file).
If another source file #includes main.h, this will stop "working".
This topic is closed to new replies.
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