C / C++ / MFC

Re: Unable to find an entry point when loading an unmanaged DLL

19-Jan-06 17:39

Hello,

I have an unmanaged C++ dll that I would like to load in a managed C++ application. I can call methods in the dll from an *unmanaged* program with no issues.

I set up the import using:

// Set up the import<br />
[DllImportAttribute("lib.dll")] int function();

The project is correctly set to find the libary files.

When I run the compiled program, it throws an execption at the line:

function();

The exception is:

An unhandled exception of type 'System.EntryPointNotFoundException' occurred in testManaged.exe<br />
<br />
Additional information: Unable to find an entry point named function in DLL lib.dll.

This error indicates that it cannot find the function in my libarary, but I know the function is there and accessible because I can access it from unmanged code. Is there something wrong with my import statement? Anything else?

Thanks,

--Jordan

-- modified at 23:40 Thursday 19th January, 2006

Stephen Hewitt19-Jan-06 17:58

Stephen Hewitt

19-Jan-06 17:58

Try adding a ExactSpelling=true. I think the syntax would be like this:

<br />
[DllImportAttribute("lib.dll", ExactSpelling=true)] int function();<br />

But I'm not a dotNET guru...

Steve

Re: Unable to find an entry point when loading an unmanaged DLL

Jordan C. Atlas19-Jan-06 18:03

Re: Unable to find an entry point when loading an unmanaged DLL

19-Jan-06 18:03

The ExactSpelling attribute did not fix it (I get the same exception), but thank you for the suggestion.

--Jordan

Stephen Hewitt19-Jan-06 18:05

Stephen Hewitt

19-Jan-06 18:05

Can you post the declaration of the unmanaged function (so I can check the calling convention) - The C++ code.

Steve

-- modified at 0:06 Friday 20th January, 2006
FIXED errors

Re: Unable to find an entry point when loading an unmanaged DLL

Jordan C. Atlas19-Jan-06 18:14

Re: Unable to find an entry point when loading an unmanaged DLL

19-Jan-06 18:14

Stephen,

The function was declared as:

LIB_API int function(void);

where I have

#define LIB_API __declspec(dllexport)

Changing it to:

extern "C" LIB_API int function(void);

seems to have fixed the problem -- I'd be happy to hear an explanation for that if you have one.

Thanks,

--Jordan

-- modified at 0:14 Friday 20th January, 2006

Jordan C. Atlas19-Jan-06 18:11

19-Jan-06 18:11

I found the problem -- I was using an improper function prototype for the shared function. I reset the import to say:

// Set up the import<br />
[DllImportAttribute("lib.dll")] <br />
extern "C" int function();

I'm not sure why the extern "C" is necessary, so here is a link to the article that tipped me off:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconcreatingprototypesinmanagedcode.asp[^]

Thanks again to Stephen for his suggestion.

--Jordan

NT Services

udaybhaskar_nori19-Jan-06 17:18

udaybhaskar_nori

19-Jan-06 17:18

I need to develop an exe which runs as an NT Service. My requirement is that I need to spy a folder and encrypt all the new files that come into that folder.
Only the adminstrators should have permissions to stop the service.

I figured out how to spy the folders from code in this site.
Also got the code to run as an NT Service, but could not write an event which on start of NT Service invokes the part to watch directories. And on stop of service unwatches the directory.

Please help me out. Also suggest me how to achieve this if the earlier project in this site could be used.
Ref: http://www.codeproject.com/system/cntservice.asp

Udaybhaskar

ThatsAlok19-Jan-06 17:48

ThatsAlok

19-Jan-06 17:48

udaybhaskar_nori wrote:
lease help me out. Also suggest me how to achieve this if the earlier project in this site could be used.Ref: http://www.codeproject.com/system/cntservice.asp

Mr. Naughter Provided a Demo application with the Service.. where he derived a class from CNTService and created a beeping program.. you have to see code of void CMyService::ServiceMain(DWORD /*dwArgc*/, LPTSTR* /*lpszArgv*/)

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta VC Forum Q&A :- I/ IV

udaybhaskar_nori19-Jan-06 17:52

udaybhaskar_nori

19-Jan-06 17:52

Thanks for your prompt reply.

Yeah I have seen that program. In place of the beep I tried to keep an AfxMessageBox. The service stops responding. Can I write MFC code in that place.
Do I need to call any other method there, before calling MFC code?

Thanks in advance.

Udaybhaskar

Prakash Nadar19-Jan-06 17:57

Prakash Nadar

19-Jan-06 17:57

may be this would be usefull http://www.codeproject.com/file/DirCheck.asp[^]

-Prakash

[Message Deleted]

kakan19-Jan-06 19:44

kakan

19-Jan-06 19:44

[Message Deleted]

ThatsAlok19-Jan-06 21:05

ThatsAlok

19-Jan-06 21:05

kakan wrote:
A service doesn't have a window so you should avoid all GUI operations, including MessageBox in a service

Little Contradiction Sir, I had placed Dialog Box in the service and it works fine for me.. moreever I have used winsock in that project too.

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta VC Forum Q&A :- I/ IV

ThatsAlok19-Jan-06 21:11

ThatsAlok

19-Jan-06 21:11

udaybhaskar_nori wrote:
Yeah I have seen that program. In place of the beep I tried to keep an AfxMessageBox.

You service stop responding because message box have a modal loop!, so you have to respond to MessageBox before interecting with service, Now as Mr. PJ naughter service is not desktop interective by default, you have to make it desktop interective to respond to messagebox and make it messagepump running.

for making Service desktop interective :-
Open Computer Management--> choose Service and Application Tree Item --> choose service tree sub item---> find you service is listed service -> right click on service and choose properties-> now choose LOG ON tab and Check Allow service to interect with desktop check box

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers, Alok Gupta VC Forum Q&A :- I/ IV

udaybhaskar_nori20-Jan-06 0:26

udaybhaskar_nori

20-Jan-06 0:26

Yes it worked for me that way. But I am getting a lot of debug assetions in debug mode. I am creating a reference to a class and calling a method of that class. What could be the reason? Are there any exceptions in using dialog code.

Udaybhaskar

Question about MFC ActiveX Control Function

ThatsAlok20-Jan-06 0:41

ThatsAlok

20-Jan-06 0:41

udaybhaskar_nori wrote:
What could be the reason? Are there any exceptions in using dialog code.

I have read some where you cannot run the Service in debug mode

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV

godspeed12319-Jan-06 17:11

godspeed123

19-Jan-06 17:11

Hi,

I have used the MFC Wizard to create a function such as this one, and it produced the following,
when I run the ActiveX it crashes the program, I had posted a similar problem before using variants and it fixed when Steve mentioned that a [out] is required in from of a pointer so I attempted it here and I got an error

Before Steve's fix
[id(10), helpstring("method testing")] void testing(BSTR * test );

After Steve's Fix
[id(10), helpstring("method testing")] void testing([out]BSTR * test );

This didnt do it for this case, I havent done anything else to the function, all I'm doing is assigning a fixed BSTR to the pointer, but even with this comment I get an error telling me that there is a type mismatch

Any help would be greatly appreciated

build project with chosen icon

leenmie19-Jan-06 15:54

leenmie

19-Jan-06 15:54

I want to build my project whose execute file (.exe) have an icon I chose. How could i do it ?

Ryan Binns19-Jan-06 17:23

Ryan Binns

19-Jan-06 17:23

The first icon (lowest numbered identifier) in the resource section of your executable will be used as the application icon. Just add an icon to your project and give it the ID 1.

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

Rajesh R Subramanian19-Jan-06 17:50

Rajesh R Subramanian

19-Jan-06 17:50

Assuming you are using MFC, the ID of your application's icon will be IDR_MAINFRAME (i think.. check that). Now, import the icon you want and rename the ID of it to IDR_MAINFRAME (delete the previous icon before this or rename the ID of that to something else).

Regards,
Rajesh R. Subramanian

You have an apple and me too. We exchange those and We have an apple each.
You have an idea and me too. We exchange those and We have two ideas each.

leenmie19-Jan-06 22:10

leenmie

19-Jan-06 22:10

No, im using raw api. That's the problem.