Thread: static data members in structure

Hi everybody!

I am in great trouble regarding structures.It is as follow:-

I am developing a DLL in C++ using VC++ editor.This DLL is called by the another C++

programme to achive some functonality.

I declared a structure as follow:

Code:

typedef struct{

 static char szOriginalAddress[0x100];
 static char szRecipientAddress[0x100];
 static char szFileName[0x100];

} TExternalFilter;

#import "C:\Program Files\Common Files\System\ADO\msado15.dll" \
no_namespace rename ("EOF", "ADOEOF")


EXPORT DWORD Filter(TExternalFilter* );

This is header file in which declaration has been done.

The programme in which this header file is used  is as follow:-


BOOL APIENTRY DllMain( HANDLE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved	 )
{
    return TRUE;
}


EXPORT DWORD Filter(TExternalFilter* ExternalFilter)
{		
	static char temp[256];	
	strcpy(temp,ExternalFilter->szOriginalAddress);
}

This file is called by our main CPP program.

When i compile this program it gives following Linker error in DLL:
error LNK2001: unresolved external symbol "public: static char * __unnamed::szOriginalAddress" (?szOriginalAddress@__unnamed@@2PADA)


This error is due to variable are declare as static in DLL, but I want these member as

static only.Please tell me what code and where should I implement so that I can remove this

problem.

Added : How can I declare and define these static member variables? The linker error may be due to static variables not being defiined but only declared.


Please help in solving this problem.

I will be very thankful.

Thanks in advanced

Bhagwat

Static data members need to be defined outside the class body. Currently they just have a declaration.

Create a cpp file, #include this header, and add the following:

Code:

static char TExternalFilter::szOriginalAddress[0x100];
static char TExternalFilter::szRecipientAddress[0x100];
static char TExternalFilter::szFileName[0x100];

Now the static data of the TExternalFilter class is properly defined.

Mario F., it's a structure

I confess I'm not used to that style. But...

Code:

typedef struct {} foo;
Is the same as
struct foo {};

Isn't it?

You were talking about class.

Ah. Gotcha!

a struct is a class... at least on this forum

Originally Posted by Mario F.

I confess I'm not used to that style. But...

Code:

typedef struct {} foo;
Is the same as
struct foo {};

Isn't it?

In C++, yes.

In C, there are syntax differences in how you'd use them, pass them to functions, etc.

I really don't think you actually want these to be static.