I have a project in Visual C++ 6 with multiple source files. I want the DirectX objects to be global to all the source files not just the files they are declared in. I tried this: extern LPDIRECTDRAW7 lpDD=NULL; The extern statment didnt work. How can I do it? Thanks.

Hmm... Are you sure you used the extern keyword right?

there where you declare the value you don''t use ''extern'' you just declare it normally....

LPDIRECTDRAW7 lpDD=NULL;

in every function where you want to use it.. (draw(), whatever) you use extern LPDIRECTDRAW7 lpDD; then it is available in that function..

cya,
Phil


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quote:

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Original post by G a m e D e v
I have a project in Visual C++ 6 with multiple source files. I want the DirectX objects to be global to all the source files not just the files they are declared in. I tried this:

extern LPDIRECTDRAW7 lpDD=NULL;

The extern statment didnt work. How can I do it?

Thanks.

---

If you declare a variable extern, you can''t set it''s value in the declaration... Here''s how you would do that.

in a .H file that you will include in all your files:

extern LPDIRECTDRAW7 lpDD;

in your main file, you do:

LPDIRECTDRAW7 lpDD = NULL;

now, all your files will have access to your globals...



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Ok thanks I got it working with variables and functions. But how would I make a class avalible to multiple files using extern?

extern is really just for variables, ie. instances of classes or primitive types. Functions and classes are available to any source file that includes the function prototype or class declaration.

If you want to do it with a class I suggest using a singleton.

class singleton
{
private:
// constructor is private, werid huh?
singleton(){};
public:
static singleton& getInstance()
{
static singleton theInstance();
return theInstance;
}

}; // end of class

This way you are ensured a single instance of the class, you access the class through
singleton::getInstance()...
or alias the instance
singlton &single = singleton::getInstance();
single...

The class is created at the first call of getInstance, although
a variation is to have an init method that creates the instance (and ensures the object is properly instantiated).
Patterns are cool, m'kay

Edited by - brad_beveridge on July 19, 2001 7:25:39 PM