Managed C++/CLI

Re: Jagged arrays in MC++

21-Apr-03 19:36

Just test 21 nested structs on VS.NET 2003 Final Beta. It compiles without any problem.

Frankly, working with MC++ is sometimes frustrating. The compiler seems to be a work in progress.

Consider the ff, for instance:

System::String __gc* strTmp1 = String::Format(S"{0}, {1}, {2}",
 S"0", S"1", S"2");

System::String __gc* strTmp2 = String::Format(S"{0}, {1}, {2}, {3}",
 S"0", S"1", S"2", S"3");

The second strTmp2 will not compile simply because the MC++ does not have support for variable parameters, while C# and even VB.NET supports it.

Best regards,
Paul.

Jesus Christ is LOVE! Please tell somebody.

Jagged arrays in MC++

Alexandru Savescu15-Apr-03 4:12

Alexandru Savescu

15-Apr-03 4:12

I have a managed class and I want to declare a jagged array of doubles as a member. How do I declare this and how do I initialize it? I can do that in C#, but I have syntax problems when it comes to __gc stuff Smile | :)

Thanks!

Best regards,
Alexandru Savescu

P.S. Interested in art? Visit this!

Natty Gur15-Apr-03 4:29

Re: Jagged arrays in MC++

15-Apr-03 4:29

__wchar_t  comma __gc[] = {L','};

Paul Selormey21-Apr-03 19:59

What's the difference between VC++ and Managed C++?

21-Apr-03 19:59

Normally you use Array::CreateInstance() method to create the jagged array.

using namespace System;
using namespace System::Collections;

public __gc class Test
{
	Test()
	{
		Int32 lowerBounds[] = {200};
		Int32 lengths[]     = {10};

		_array = Array::CreateInstance(__typeof(Int32), lengths, lowerBounds);
	}

private:
	Array __gc* _array;
};

You might wish to give a C# example of what you need if the above does not answer your question. Remember you can assign (cast) Array __gc* to [].

Best regards,
Paul.

Jesus Christ is LOVE! Please tell somebody.

BoudewijnEctor14-Apr-03 8:45

BoudewijnEctor

14-Apr-03 8:45

Can anyone tell me waht the difference is between VC++ and Managed C++.

Can anyone also tell what's ATL or COM?

Thanks Smile | :)

Re: What's the difference between VC++ and Managed C++?

Maximilien14-Apr-03 8:53

Maximilien

14-Apr-03 8:53

Managed C++.

(in very short)

Is Microsoft extension to the C++ languange to support the .Net framework. The main difference, is that it introduces garbage collection, and other cool stuff.

COM, and ATL, I don't know enough to give an answer.

Max.

Maximilien Lincourt
For success one must aquire one's self

Re: What's the difference between VC++ and Managed C++?

Natty Gur14-Apr-03 18:46

How to cast a pointer to a member function into a void*?

14-Apr-03 18:46

Managed c++ - the C++ code will be run under the CLR. you can take advantage of the CLR services and be aware of its limitation (for example the CLR control the memory allocation)
COM - is a protocol used by Microsoft in the latest years (until the appearance of .Net) to enable communication, transfer of data and activation of components (DLL, EXE, OCX …) writing in different development tools and languages. As long as the provider and consumer support COM a communication can established between them.

ATL (Active Template Library) - is a library that enable c++ programmer to write components that support COM with less effort. The ATL contain templates that encapsulate many coding issue regarding to COM and let you spend more time on your application rather on COM.

Charles Liu14-Apr-03 2:45

Charles Liu

14-Apr-03 2:45

I got the code as follows:
class A{
int f(); //f defined elsewhere
}

void main()
{
void* p;
p = A::f; //it gives a compiler error
//how to cast f into p?
//My friend did that in asm, however i want an easier way.
}
Thanks in advance

Re: How to cast a pointer to a member function into a void*?

Natty Gur14-Apr-03 4:43

Re: How to cast a pointer to a member function into a void*?

14-Apr-03 4:43

System::Runtime::InteropServices::Marshal::StructToPtr(ManagedObject,PointerToVoid,true)

John R. Shaw29-Apr-03 18:41

John R. Shaw

29-Apr-03 18:41

void* p = (void*)(A::f);

C++ compilers are very strict, they want to make absolutly sure you know what you are doing (this is a good thing). If you need to do this you are probubly doing some thing wrong. I recommend that you read up on vetual base classes.

Trust in the code Luke. Yea right!

cast to c++ interface from C#

bwells14-Apr-03 0:42

bwells

14-Apr-03 0:42

I get a runtime error when I cast an object to an interface the class implments. The class and interface are both managed C++, and the cast in done in C#.

I have narrowed the problem down to a simple case:

1) C# constructs an object defined in managed C++
2) C# casts object to a managed C++ interface it implements
3) C# call method on the object after the cast.

If I do this, I get a runtime exception. I have seen an invalid cast exception, and sometimes I get a format exception that says "the format specific is not allowed...". It seems like the runtime gets very confused.

But instead if I do the following;

1) C# constructs a object defined in managed C++
2) C# stores object in variable as its actual type; not the interface
3) C# calls method on class

it all works.

The problem comes when C# casts a managed C++ object to be its interface type (the interface is also defined as a managed C++ interface).

I have not found anyone who has done what I am trying to do, and I have not found any documentaion that talks about this, so perhaps its not recommended.

Does anyone have experience mixing managed C++ and C# with interfaces defined in C++ and casts to the interface being done form C#?

thanks
Bryan

Natty Gur14-Apr-03 4:48

14-Apr-03 4:48

I got the same experience so i declared the interface in C# Dll.

bwells14-Apr-03 13:58

bwells

14-Apr-03 13:58

So if I declare an interface in C#, can I implement the interface in managed C++ successfully?

Natty Gur14-Apr-03 17:34

14-Apr-03 17:34

Yes, you can find a sample at http://www.codeproject.com/useritems/SessionState.asp.
look at the source -> tmpSessionSync project.

bwells16-Apr-03 12:57

bwells

16-Apr-03 12:57

I am trying your suggestion. But I have one problem. I have defined an C# interface with a method that returns an object.

How do I define the implementation for this method in C++?

public interface ICOSP_9054_Connection
{
object getConnection( );
}

Originally, when I declared the interface in C++, the method returned a void*. Is there a way to return a void* from a C# method? I can do fine with either approach. The problem is that for some implementors of this method, they will be asking unmanaged C++ code to return an object that I have not defined an interface for so it is easier for me to return a void* (or object).

thanks
Bryan

Natty Gur16-Apr-03 20:11

Unmanaged code to call managed code

16-Apr-03 20:11

public interface ICOSP_9054_Connection
{
object getConnection( );
}

public MyClass : public ICOSP_9054_Connection
{
public:
Object __gc* getConnection()
{

}
};

onyxbird10-Apr-03 9:43

onyxbird

10-Apr-03 9:43

I have an app which uses SDI and is written in MFC for its presistence it uses a STL vector. I need to migrate to managed C++ by changing my container to a managed container. I have tried System.Array that didn't work, and either did wrapping the vector. can you please provide a good idea I'm out of ideas.

Sul,R.

Upcoming developer only 2.5 months to go

Re: Unmanaged code to call managed code

Paul Selormey10-Apr-03 18:03

C2682: cannot use __try_cast to convert from 'gcroot<T>'

10-Apr-03 18:03

System::Array will not provide the STL vector style container. Consider System::Collection::ArrayList. You can derive from the ArrayList and add new methods which match the STL::vector to make the porting easier.

If you still have problems, then post some codes.

Best regards,
Paul.

Jesus Christ is LOVE! Please tell somebody.

Paul Selormey31-Mar-03 20:40

Re: C2682: cannot use __try_cast to convert from 'gcroot<T>'

31-Mar-03 20:40

Hello All,
I have a standard C++ class with MC++ member defined as

gcroot < System::Drawing::Brush __gc* > m_pDotNetBrush;

Somewhere in the codes, I wish to use the brush and trying to
cast it to the appropriate type:

System::Drawing::SolidBrush __gc* pBrush =
 __try_cast < System::Drawing::SolidBrush __gc* >(m_pDotNetBrush);

This, however, generates error in the form:

<br />
error C2682: cannot use __try_cast to convert from 'gcroot < T >' to 'System::Drawing::SolidBrush __gc *'<br />

I tried the other standard C++ casts and all failed with same error.
What is supposed to be done in this case?

Best regards,
Paul.

Jesus Christ is LOVE! Please tell somebody.

Paul Selormey1-Apr-03 0:51