Managed C++/CLI

Re: Managed DLL with unmanaged MFC application

11-Jul-03 5:31

stub wrote:
If so how does one setup the DLL to do this?

Yes, you can get VC6 to work with Managed DLLs, but you will need to look into the topic of COM Interop. This makes it so that a Managed DLL acts just like a COM Dll and therefore can be used by any COM compatible language (VC6, VB6, etc).

-Nathan

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Hmmm... what's a signature?

Heath Stewart11-Jul-03 5:51

Heath Stewart

11-Jul-03 5:51

There is another way besides COM interop, but it's not easy and probably not recommended (being that most of the functions and structures are undocumented).

You can host the CLR yourself using the unmanaged functions of the .NET Framework. You create a default AppDomain that creates your application's AppDomain. From there, you can actually do some things with the managed DLL, but it is a difficult process. COM interop is definitely easier, I just wanted to provide another alternative.

For more information, look-up CorBindToCurrentRuntime and CorBindToRuntimeEx. This will give you the starting points for the rest.

Reminiscent of my younger years...

LOAD "SCISSORS"

RUN

Re: Managed DLL with unmanaged MFC application

rahtrow11-Jul-03 8:31

rahtrow

11-Jul-03 8:31

This article may point you in the right direction...

Walkthrough: Exploring COM Interoperability with ATL and Managed Extensions for C++[^]

Managed strings and buffers to nonmanaged

jspano10-Jul-03 7:58

10-Jul-03 7:58

I just jumped in to MC and am having some string problems.

I have 2 functions in c++ that I wanted to wrap with MC to use from c#. The def are as follows.

<br />
int EncryptString (wchar_t * pszString, wchar_t * & pszResultString);<br />
int DecryptString (wchar_t * pszString, wchar_t * & pszResultString);<br />

The first param of both is a string. the second is a string that acts as a buffer for the return value. How do I get these into MC?
I want to have a managed function that will take either 2 strings or a string and a StringBuilder.

<br />
void CAES::DecryptStr(String* DecString, StringBuilder* Buff)<br />
	{<br />
<br />
	}<br />

What do I need to put in the function to get DecString and Buff into something I can pass DecryptString? I need Buff to hold the output and return to c# intact etc.

TIA

Nathan Blomquist10-Jul-03 8:32

10-Jul-03 8:32

Hello,

Check out System.Runtime.InteropServices.Marshal. Specifically: the StringTo... and PtrTo... methods.

Hope this helps,
Nathan

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Hmmm... what's a signature?

jspano11-Jul-03 3:23

11-Jul-03 3:23

Thanks for the reply. I have been working with that for a while now. I got the simple wchar_t to go easily. Do you know how to do the string builder buffer? I need it to copy to the wchar_t and then get whatever comes out back into the string builder.

Also do you know of any good reading on this subject? I have found lots of stuff, just nothing more advanced than a simple string to string conversion.

Thanks!

This is what I have so far in the decrypt sub.

<br />
wchar_t __nogc* pStr = static_cast<wchar_t*>(Marshal::StringToHGlobalUni(EncString).ToPointer()); <br />
wchar_t __nogc* pBuf = ; //what goes here?<br />
int Ret;<br />
<br />
Ret = DecryptString(pStr,pBuf);<br />
//how do I get pBuf back into the stringbuilder<br />

Nathan Blomquist11-Jul-03 4:25

11-Jul-03 4:25

To copy the StringBuilder into the pBuf, you should be able to exactly the same thing that you did with the first String.

<br />
String* pStringTemp = Buf->ToString();<br />
wchar_t __nogc* pBuf = static_cast(Marshal::StringToHGlobalUni(pStringTemp).ToPointer());<br />

Then to copy back into the StringBuilder just do:

Buff->Remove(0,Buf->Length); // this clears the StringBuilder<br />
Buff->Append(new String(pszResultString)); // adds the result to the StringBuilder

Hope this helps get you going again... (not tested Frown | :(

-Nathan

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Hmmm... what's a signature?

jspano11-Jul-03 5:14

11-Jul-03 5:14

Thanks a lot!! That got me there.

Boy MC is giving me a headache. Frown | :(

Nathan Blomquist11-Jul-03 5:28

11-Jul-03 5:28

Glad that I could be of help. I forgot to answer your question about reading material. I don't have any good articles off the top of my head, but a good book on the subject is:
Programming with Managed Extensions for Microsoft Visual C++ .NET--Version 2003[^]

Just the first chapter alone is worth the money. The author should give me a little cash, I think I have posted that book 3 times now here... oh well... I like it a lot... Big Grin | :-D

I like MC++ but it is kind of a pain... It allows a lot of cool things to happen.
Yea, legacy code support Dead | X|

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Hmmm... what's a signature?

jspano11-Jul-03 6:48

11-Jul-03 6:48

OK I'm about to throw MC out the window.

Here is my code

<br />
void CAES::EncryptStr(String* EncString, StringBuilder* Buff)<br />
	{<br />
		wchar_t __nogc* pStr = static_cast<wchar_t*>(Marshal::StringToHGlobalUni(EncString).ToPointer()); <br />
		String* pStringTemp = "";<br />
		wchar_t __nogc* pBuf = static_cast<wchar_t*>(Marshal::StringToHGlobalUni(pStringTemp).ToPointer());<br />
<br />
		int Ret;<br />
<br />
		Ret = EncryptString(pStr,pBuf);<br />
		<br />
		Buff->Remove(0,Buff->Length); // this clears the StringBuilder<br />
		Buff->Append(new String(pBuf)); // adds the result to the StringBuilder<br />
<br />
	}<br />

This worked fine a few mins ago. NOTHING HAS CHANGED IN THE WHOLE PROJECT!!! Now I get an unhandled exception in mscorlib. It is a stack overflow exception. It happens on the Buff->Remove line. If I take it out it happens on the Buff->Append line.

The only think I did was make some functions in the non managed class I have private with the private: keywork in my header. After this it broke. I removed the private keyword and it's still broke.

Any ideas?

Further info: It happens when I call any framework thing after comming back from the dll also. I tried to show a messagebox and it failed also. This was after the call to EncryptString. I removed the Buff-> stuff so the method would return. It doesn, but I get the exception after it gets back now.

Nathan Blomquist11-Jul-03 7:20

11-Jul-03 7:20

Shouldn't you have to pass a type to the static_cast method (operator)?

Like:

<br />
wchar_t __nogc* pStr = static_cast<wchar_t*>(Marshal::StringToHGlobalUni(EncString).ToPointer()); <br />
String* pStringTemp = "";<br />
wchar_t __nogc* pBuf = static_cast<wchar_t*>(Marshal::StringToHGlobalUni(pStringTemp).ToPointer());<br />

I have no idea if that is a problem that you are having... Also you said you changed header file stuff... Did you make sure to do a clean and rebuild?

[Edit] You don't really need to do the String* pStringTemp at all... all you are doing is allocating an empty string... So you only need to declare pBuf and pass it in by reference like you are doing... Also, did you make sure to new the pBuf inside of your EncrString function? else you will be writing to a zero length char buffer...[/Edit]

-Nathan

P.S. about the static cast stuff... you can probably ignore me, I found that you need to use the little code project buttons to make them show up... Blush | :O

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Hmmm... what's a signature?

jspano11-Jul-03 7:23

11-Jul-03 7:23

Yeah, I did a clean build. I restored the header file from backup. No luck.

Here is the kicker...
I ported another class to see if it was with all of them or just this one. It works fine. And guess what, the other one works fine now also... Go figure. I have no idea what went wrong. Maybe it will do it again??

Oh well. Thanks for all your help and info.

jspano11-Jul-03 7:51

11-Jul-03 7:51

And yet once again it won't work. I added a 3rd class that doesn't work either. an exception about a null pointer from mscorlib.

Nathan Blomquist11-Jul-03 11:02