Managed C++/CLI

Re: Warnings in c++/cli that make me a lot of headache

30-Aug-07 1:53

First issue: If native code executes before managed code, your application may have problems with loader lock: http://msdn2.microsoft.com/en-us/library/ms172219(vs.80).aspx[^]

Second Issue: If the dr["clmId"] is an object, for example a String^, the compiler believes you are trying to set the object to NULL with zero which is not permitted.

"We make a living by what we get, we make a life by what we give." --Winston Churchill

hansipet30-Aug-07 2:19

Re: Warnings in c++/cli that make me a lot of headache

30-Aug-07 2:19

Okay I understand the problems, but what I can do? How I can have the warnings away (not only with pragma)?

1) I need unmanaged classes and there I have static instances...
2) I understand also this, but in this case the column is a integer...What I have to do?

Best regards
Hansjörg

George L. Jackson30-Aug-07 2:53

Re: Warnings in c++/cli that make me a lot of headache

30-Aug-07 2:53

I am only seeing small snippets of your code and don't know anything about your programming requirements. So, I can only give you general advice about what I think may be wrong.

"We make a living by what we get, we make a life by what we give." --Winston Churchill

hansipet30-Aug-07 20:19

Re: Warnings in c++/cli that make me a lot of headache

30-Aug-07 20:19

Hello,

advice 2 was really good. It works! The only thing that I don't have tested Frown | :-(

for the first point:

I have a mixed c++/cli (for speed reasons) program. And for that I have in a few assemblies classes which are totally unmanaged:

<br />
#pragma managed(push,off)<br />
class Test<br />
{<br />
static std::wstring teststr;<br />
<br />
//some other functions...<br />
}<br />

In this class I don't have the possibility to use a managed string class. And the only way (that I know) to initialize the static member is

<br />
std::wstring Test::teststr = L"";<br />

Isn't it?

What do you do in that case?

Best regards
Hansjörg

George L. Jackson31-Aug-07 0:07

Re: Warnings in c++/cli that make me a lot of headache

31-Aug-07 0:07

I will try to answer your question later on after work. However, why are you writing native code in assemblies compiled by /clr? I know you said for speed reasons. However, are you aware of managed to unmanaged and unmaanaged to managed transitions (thunks) which act like speed bumps in your application. Nevertheless, if it is the only way to write the program, I understand.

"We make a living by what we get, we make a life by what we give." --Winston Churchill

hansipet31-Aug-07 1:57

Re: Warnings in c++/cli that make me a lot of headache

31-Aug-07 1:57

Thank you very much!

Yes I know about the speed bumps but I'm careful with every transition (mostly from windows forms to unmanaged code)...

Best regards
Hansjörg

George L. Jackson31-Aug-07 9:25

Re: Warnings in c++/cli that make me a lot of headache

31-Aug-07 9:25

The only way I could get native static objects to work in managed code was to place them inside of static functions or static methods. For example:

#pragma managed(push, off)
using std::wstring;
 
class Foo
{
public:
 
	static const wchar_t* State(const wchar_t* value = 0)
	{
		static std::wstring state= L"";
 
		if (value != 0)
			state = value;
 
		return state.c_str();
	}
 
};
#pragma managed(pop)
 
using namespace System;
 
int main(array<System::String ^> ^args)
{
	String^ str1 = gcnew String(Foo::State());
 	
	Foo::State(L"Hello!");
 
	String^ str2 = gcnew String(Foo::State());
 
	Console::WriteLine(str1);
	Console::WriteLine(str2);
 	
    return 0;
}

"We make a living by what we get, we make a life by what we give." --Winston Churchill

hansipet1-Sep-07 8:55

Re: Warnings in c++/cli that make me a lot of headache

1-Sep-07 8:55

Thank you very much!!!

George L. Jackson30-Aug-07 3:51

mixed types are not supported?

30-Aug-07 3:51

Issue #2: Have you tried manually boxing the zero?

"We make a living by what we get, we make a life by what we give." --Winston Churchill

Rui A Sousa29-Aug-07 6:45

Rui A Sousa

29-Aug-07 6:45

Hello!

I have this code:

(...)
static double U[5];
(...)

And, when i compile i see this error:

error C4368: cannot define 'U' as a member of managed 'bojoo::Class1': mixed types are not supported

Frown | :(

How i fix it?

Thank´s!

Rapbs

Re: mixed types are not supported?

led mike29-Aug-07 7:06

Re: mixed types are not supported?

29-Aug-07 7:06

Rui A Sousa wrote:
How i fix it?

I would like to clarify what you are asking for. Do you want someone to tell you how to fix the code or, do you want to understand the issue so that it will never be a problem for you again?

Mark Salsbery29-Aug-07 8:07

Making Dialog Boxes Modal

29-Aug-07 8:07

One feature in Visual Studio I find useful is the pressing the F1 key on error messages I don't
understand Poke tongue | ;-P

For example - your error shows me:

"You cannot embed a native data member in a CLR type.

You can, however, declare a pointer to a native type and control its lifetime in the constructor
and destructor and finalizer of your managed class (see <mshelp:link tabindex="0" keywords="0d09d3f1-13a0-4041-8178-402aad667edd">Destructors and Finalizers in Visual C++
for more information)."

Cheers,
Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

gunner_uk200029-Aug-07 5:58

gunner_uk2000

29-Aug-07 5:58

2 classes which are dialogues.

On the 1st dialog, I have button that when pressed opens another dialog. I can't work out how to make the second one modal.

I'm calling the second Dialog boxes show() method in the DlgProc method as below.

LRESULT CALLBACK ExodusDisplayOptions::DlgProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam){<br />
	//TODO: Comment and clean up.<br />
	switch(message)<br />
    {<br />
		case WM_INITDIALOG:<br />
		{<br />
			//do some stuff<br />
		}<br />
		break;<br />
        case WM_DESTROY:<br />
            PostQuitMessage(0);<br />
		break;<br />
		case WM_COMMAND:<br />
		{<br />
			switch (LOWORD(wParam))<br />
			{<br />
			case WM_CLOSE:				<br />
				return (TRUE);<br />
			break;<br />
			case IDC_CLOSE:<br />
				EndDialog(hDlg, LOWORD(wParam));<br />
				return (TRUE);<br />
			break;<br />
			case IDC_BUTTONDISPLAY:<br />
				ExodusHazardDisplayOptions *haz = new ExodusHazardDisplayOptions(m_this, m_opts);<br />
				bool i = haz->Show();<br />
			break;<br />
<br />
<br />
			}<br />
<br />
			<br />
		}	<br />
        break;<br />
        default:<br />
            return DefDlgProc(m_this, message, wParam, lParam);<br />
    }<br />
    return 0;<br />
}

Any ideas?

Re: Making Dialog Boxes Modal

Mark Salsbery29-Aug-07 8:16

Can not convert from short __gc* to short*

29-Aug-07 8:16

gunner_uk2000 wrote:
Any ideas?

You're in the wrong forum Smile | :)

What does "haz->Show()" do? Is it creating a modal dialog? For a modal dialog
you need to call one of the DialogBox___() APIs.

Off topic... the "case WM_CLOSE" in response to WM_COMMAND looks suspicious.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Thanks for all the fish28-Aug-07 23:41

Thanks for all the fish

28-Aug-07 23:41

Hi All

I am creating a managed wrapper class for a c++ unmanaged class.While I am calling a function in managed class and passing a short paramater as reference

1.short MCDPTAdminClass::listPrinters() //managed class
2.{
3. m_CDPTAdminClass->listPrinters(&numPrintersFound);
//m_CDPTAdminClass object of unmanaged class and short numPrintersFound
return numPrintersFound;

}

I am getting an error "Can not convert from short __gc* to short*" at line "3"
Can anyone help me to resolve this problem .

thanks in advance

led mike29-Aug-07 5:16

29-Aug-07 5:16

Thanks for all the fish wrote:
Can anyone help me to resolve this problem

I would like to clarify what you are asking for. Do you want someone to tell you how to fix the code or, do you want to understand the issue so that it will never be a problem for you again?

Mark Salsbery29-Aug-07 8:17

29-Aug-07 8:17

Thanks for all the fish!

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

George L. Jackson29-Aug-07 12:05

29-Aug-07 12:05

Mark Salsbery wrote:
Thanks for all the fish!

Does that have some kind of religious significance?

"We make a living by what we get, we make a life by what we give." --Winston Churchill

Mark Salsbery29-Aug-07 12:45

29-Aug-07 12:45

George L. Jackson wrote:
Does that have some kind of religious significance?

Only in my religious commitment to keeping led mike's fish-filet analogy alive!

Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

George L. Jackson29-Aug-07 13:00

Calling into .NET Class Lib from a C++ app

29-Aug-07 13:00

HeHe! I saw the original posts!

"We make a living by what we get, we make a life by what we give." --Winston Churchill

concoran28-Aug-07 21:04

concoran

28-Aug-07 21:04

Is it possible to call into a .NET class library from a VC60 C++ app? If yes, how?

I wanted to create a middle layer between C++ app and .NET class library - sort of a wrapper for .NET class library. Towards that end, in VS2005, I created a C++ Win32 Dll. I have turned on CLR option from Project->Properties>Configuration. But in this project, I couldn't figure out how do I instantiate ClassLibrary and make calls into it. Can someone please enlighten?

Thanks.

None

Re: Calling into .NET Class Lib from a C++ app

led mike29-Aug-07 5:13

Re: Calling into .NET Class Lib from a C++ app

29-Aug-07 5:13

concoran wrote:
Can someone please enlighten?

It sounds like this is your initial use of C++/CLI? If so I recommend learning about it first before you approach your project. There are almost endless articles, tutorials and sample/example projects available here and on MSDN to educate you about the power of C++/CLI.

concoran30-Aug-07 14:05

concoran

30-Aug-07 14:05

Hi Led,

Yes, I am new to CLI, but not to C++. I am also new to Codeproject. Can you pls point to where I can find articles on this website?

Thanks in advance.

None

Re: Calling into .NET Class Lib from a C++ app

led mike31-Aug-07 4:20