using cpp dll in c# code

Question

I'm trying to use native c++ dll inside a c# application.

I followed this article to get started.

Its working fine while the dll using only c files (like in the tutorial), but when using cpp files I cant make it work.

using the dumpbin tool I can see that my exported function names changed. for example a function call 'next' changed to '?next@@YAHH@Z' and when I'm trying to call it in the c# code it cant find it.

my dll code is:

__declspec(dllexport)
int next(int n)
{
    return n + 1;
}

the c# code

[DllImport("lib.dll", CallingConvention = CallingConvention.Cdecl)]
    extern static int next(int n);

its the same code while using c file or cpp files

Thanks in advance Amichai

Please post your code.

Wagner DosAnjos
– Wagner DosAnjos

2016-11-03 06:29:22 +00:00
Commented Nov 3, 2016 at 6:29 — Wagner DosAnjos
– Wagner DosAnjos, Commented Nov 3, 2016 at 6:29
i dont understand what you mean by cpp

Vijunav Vastivch
– Vijunav Vastivch

2016-11-03 06:35:12 +00:00
Commented Nov 3, 2016 at 6:35 — Vijunav Vastivch
– Vijunav Vastivch, Commented Nov 3, 2016 at 6:35
@wdosanjos, thanks. i added my code to the question.

amichai
– amichai

2016-11-03 06:35:36 +00:00
Commented Nov 3, 2016 at 6:35 — amichai
– amichai, Commented Nov 3, 2016 at 6:35
What about your C# code?

Wagner DosAnjos
– Wagner DosAnjos

2016-11-03 06:37:02 +00:00
Commented Nov 3, 2016 at 6:37 — Wagner DosAnjos
– Wagner DosAnjos, Commented Nov 3, 2016 at 6:37
@wdosanjos, i added the c# code too. Thanks.

amichai
– amichai

2016-11-03 06:38:35 +00:00
Commented Nov 3, 2016 at 6:38 — amichai
– amichai, Commented Nov 3, 2016 at 6:38

Community · Accepted Answer · 2017-05-23 10:29:21Z

2

What you are attempting to do is to make a trampoline function, to externalize the use of your C++ objects.

What you are experiencing is called symbol mangling. It is a c++-specific way of naming the symbols (like the functions) in a dynamic library and an executable, to enable polymorphism.

You have to specify that you want to cancel the mangling effect by using an extern "C" statement in your library code, just like this:

extern "C" __declspec(dllexport)
int next(int n)
{
    return n + 1;
}

More on this here: Exporting functions from a DLL with dllexport

edited May 23, 2017 at 10:29

CommunityBot

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answered Nov 3, 2016 at 6:50

Christopher J.

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1 Comment

amichai Over a year ago

Thanks a lot. helpedme very much

Abhishek Kumar · Accepted Answer · 2016-11-03 06:47:47Z

0

Please provide the Entry Point

An example below

[DllImport("lib.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "next", CharSet = CharSet.Ansi)]
static extern int next(int n);

Hopefully It helps.

answered Nov 3, 2016 at 6:47

Abhishek Kumar

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