CODEWITHSUNDEEP
cdllvisual-studio-2015
user3533030
user3533030

Reputation: 449

Debugging a DLL for C w/Visual Studio 2015

I'm writing a DLL for an existing application. The DLL is designed to interface to commercial software who's functionality can be enhanced by adding a user defined feature with a DLL.

My DLL compiles and the application can utilize the features, but I want to debug it. It is difficult for me to attach to the process and debug when the commercial software is calling the DLL. Instead, I'd like to build separate code to test the DLL.

All the examples I can find w/DLL's are for C# or C++. I can't quite understand how to do this in C. I seem to be stuck at importing the DLL or referencing the library in the linker.

I've inserted:

__declspec(dllimport) int UserDefinedSurface4(USER_DATA *UD, FIXED_DATA4 *FD);

but I get:

LNK2019 unresolved external symbol "__declspec(dllimport) int __cdecl UserDefinedSurface4(struct USER_DATA *,struct FIXED_DATA4 *)" (__imp_?UserDefinedSurface4@@YAHPEAUUSER_DATA@@PEAUFIXED_DATA4@@@Z)

Following advice for C# and C++, I've added a path to the DLL in my project using: Properties->Linker->Input->Additional Dependencies with an explicit path: "D:......\mydll.lib" (that seems kind of brittle... is this right or should I use a relative path or ...?)

Furthermore, I also inserted:

#pragma comment(lib, "D:\\...\\mydll.lib")

and I have included the project with the DLL in my references. What's missing?

Upvotes: 0

Views: 83

Answers (1)

Nikita
Nikita

Reputation: 6427

Your dll import looks fine.

Check the name of the exported function. Good tool for this task is "Dependency Walker". If your dll compiled as C++, function name can be mangled. To prevent name mangling your export definition in DLL project should be:

extern "C" __declspec(dllexport) int UserDefinedSurface4(USER_DATA *UD, FIXED_DATA4 *FD);

In your application specify Linker -> Additional Library Directories to your library directory and in Linker -> Input specify additional dependency mydll.lib. After that check Linker -> Command Line parameter, it should contains:

"mydll.lib" /LIBPATH:"d:\yourlibrarydir\"

Upvotes: 1

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