Storing a static dictionary of class instances - Managed C++/CLI Discussion Boards

jspano18-Jul-03 16:41

18-Jul-03 16:41

Thanks, I did that and now I get

fatal error C1190: managed targeted code requires '#using <mscorlib.dll>' and '/clr' option

I did include mscorlib.dll.

To test I started a brand new .net console app and added a cpp file that I set to compile non managed. the only code in it is

#include "stdafx.h"

I get the same compile error.

Edit - Ok fixed it. Removed the /clr option. That fixed it.

Re: debug managed and unmanaged code

jspano18-Jul-03 8:56

jspano

18-Jul-03 8:56

I've been able to resolve most of this. I started out with a fresh project from scratch. The Stackoverflow ended up going away when I removed the /noentry option. I know it's supposed to be there, but it works without it for now.

Re: debug managed and unmanaged code

Nathan Blomquist21-Jul-03 1:58

Nathan Blomquist

21-Jul-03 1:58

What was your final conclusion about debugging mixed code?

From what I can tell, you cannot jump into directly compiled C++ code. Only if the compiler sees that it can compile the C++ code to MSIL can you then jump into it from MC++.

NOTE: About the StackOverFlow problem, did you ever try putting a __nogc in front of the pointer?

wchar_t __nogc* chrs = new wchar_t[sz];

-Nathan

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Re: debug managed and unmanaged code

jspano21-Jul-03 2:05

jspano

21-Jul-03 2:05

I think the overflow was from lack of knowledge. From some ideas I got from leppie it has gone away. I removed the noentry option and the /clr option from the main project. I then did the /clr option individually for managed files and turned it off for nonmanaged files. It works much better now. I know I hade the __nogc* on my pointer to the managed string I sent in as a param. I don't think I had it on my pointer to a wchar_t block. I'll add that also as another precaution.

For debuging I am still up in the air. I haven't gotten it to work in a real project when you mix managed and unmanaged. I have gotten it to work with a quick test project. I still might be wrong in the test project though.

I created a .net console app. In the cpp file it gives you, I added a function called MyFunct() and put a pragma unmanaged before it. Then in the main function I called it. It stepped into it fine. Granted this isn't a dll like my other project and it is very simple. If I have time today, I will experiment some on it.

How To Efficiently Copy Int32 to unsigned char __gc []

T R B16-Jul-03 5:56

T R B

16-Jul-03 5:56

I'm writing data to the network and I'm having trouble doing a task that would be very simple in unmanaged C++: write an Int32 to the stream. The NetworkStream class takes a byte array as a parameter in Write(). I'm not sure how to efficiently convert an Int32 to a byte array. Sure, I could use division a squeeze out a byte at a time, but that's hardly efficient. Any ideas on how to copy the 4 bytes that are an integer into an unsigned char __gc []?

Thanks in advance,

Tim

Re: How To Efficiently Copy Int32 to unsigned char __gc []

Italo Silveira16-Jul-03 7:00

Italo Silveira

16-Jul-03 7:00

Take a look at BitConverter.GetBytes().

Re: How To Efficiently Copy Int32 to unsigned char __gc []

T R B16-Jul-03 7:05

T R B

16-Jul-03 7:05

I knew there had to be an easy way to do it, but I couldn't find it. Thanks! Smile | :)

Storing a static dictionary of class instances

Jeremy Osner15-Jul-03 5:36

Jeremy Osner

15-Jul-03 5:36

Something I frequently need to do in my programs, is to store at static linkage a dictionary of currently active instances of a particular class. Managed C++ makes this a little difficult; I have found two ways to do it. Both have advantages and drawbacks; I would like to get peoples feedback about which is better.

The first method is, to make the dictionary itself a managed object. For some reason I can't quite figure out, you are allowed to declare static pointers to managed types if they are declared as static members of a managed class. This makes no sense to me but is true. So take this code fragment:

__gc class A
{
static HybridDictionary *instances;
static int iInstance;

int tag;

public:
A()
{
if (instances == 0)
instances = new HybridDictionary;
tag = ++iInstance;
instances->Add(__box(tag), this);
}
void Destroy()
{
instances->Remove(__box(tag));
if (instances->Count == 0)
instances = 0;
}
static A *Lookup(int tag)
{
if (instances == 0)
return 0;
return dynamic_cast instances->Item[__box(tag)];
}
};

The big drawback to this method is, garbage collection no longer works. You have to actively call Destroy() to get an A to remove itself from the map, because the map contains a reference that will otherwise prevent the object from being destroyed.

The other method is, make the dictionary a non-managed class and use __pin to convert the instance pointer into a non-managed pointer. The main drawback here (I think) is that the documentation says not to do it. Consider the following code (assume that the InstanceMap class has been defined and takes non-managed pointers to void):

__gc class B
{
static InstanceMap instances;
static int iInstance;

int tag;

public:
B()
{
tag = ++iInstance;
B __pin *pThis = this;
instances.Add(tag, pThis);
}
~B()
{
instances.Remove(tag);
}
static A *Lookup(int tag)
{
return (B *) instances.Item(tag);
}
};

I have not actually tried this yet and now realize that I had not completely thought out the Lookup() function -- will the compiler be able to convert the void * sent back from Item() to a B *? If so this method seems way cleaner and better, and allows me to use garbage collection. Any thoughts?

Jeremy

READIN writin rhythmetic

Re: Typos

Jeremy Osner15-Jul-03 6:19

Jeremy Osner

15-Jul-03 6:19

Scuse the typos -- B::Lookup should of course return B *; and insert indentations as appropriate.

READIN writin rhythmetic

Re: Storing a static dictionary of class instances

Jeremy Osner15-Jul-03 6:34

Jeremy Osner

15-Jul-03 6:34

Okay, I see now that the problem with solution B is that instances of B can be moved on the managed heap after the __pin pointer is out of scope. So never mind that idea... Any comments on the first, more messy solution? Any ideas for tidying it up?

READIN writin rhythmetic

Rule of Three for Managed C++

mond_m15-Jul-03 4:54

mond_m

15-Jul-03 4:54

When using the Managed C++ compiler, will the compiler generate any of the missing 'Rule of Three' methods if they are missing? ie, if I don't provide a default ctor, dtor, copy ctor or an op=, what of these will get generated by the Managed compiler?

Re: Rule of Three for Managed C++

Tom Archer18-Jul-03 7:38

Tom Archer

18-Jul-03 7:38

No.

Cheers,
Tom Archer
Inside C#,
Extending MFC Applications with the .NET Framework
It's better to listen to others than to speak, because I already know what I'm going to say anyway. - friend of Jörgen Sigvardsson

date class problem

Forever8214-Jul-03 21:55

Forever82

14-Jul-03 21:55

ur help will be bless by the lord ..amen

how to implement a class date ?(class,inheritance,control structures) included above method inside.

a method to ensure user entered 1st date return true(or 1) before the second date to return false(or 0)

another method Christmas which given a date, should return the number of days until the next Christmas day(december25).

another method ..given two dates, return the no. of days between the given two dates. The program should cope with dates having different months.

HOW TO MAKE A SIMPLE C SOLUTION

eggie513-Jul-03 14:50

eggie5

13-Jul-03 14:50

How do I make a simple C solution in VS.NET??? just a C console application...

/\ |_ E X E GG

Re: HOW TO MAKE A SIMPLE C SOLUTION

leppie14-Jul-03 7:22

leppie

14-Jul-03 7:22

If the file extension is .c it will automatically compile to C. You can also change the compiler behaviour in the projects properties.

leppie ::AllocCPArticle(Generic DFA State Machine for .NET);

Re: HOW TO MAKE A SIMPLE C SOLUTION

eggie514-Jul-03 10:17

eggie5

14-Jul-03 10:17

I have some C code for sending data though the parallel port, but the thing is that it uses things that are exclusinve to linux such as "peek" in it, and it wont complie in wideows...

any idea of how I could complie this on XP?

/\ |_ E X E GG

Re: HOW TO MAKE A SIMPLE C SOLUTION

John M. Drescher15-Jul-03 5:02

John M. Drescher

15-Jul-03 5:02

It will not compile and run on NT 4.0 or better (Win2K, XP, Win2003 ...) because a user application is not allowed to access the hardware directly. You must write or use a device driver for this. I think if you search this site you will find one. If my memory is correct P.J. Naughter wrote one.

John

Managed DLL with unmanaged MFC application

stub11-Jul-03 5:17

stub

11-Jul-03 5:17

I'm just starting to dive into Visual Studio .NET 2003 and have been attempting to find the answer on how I can use C++ managed DLL's with an older VC6.0 MFC application. Here's the scenario:

I have several large MFC applications that currently use functions contained in MFC DLL's. These DLL's aren't large so converting the DLL's to a true managed DLL in .NET is not cumbersome however, attempting to convert the applications at this stage would not be feasible. The converted DLL's will also be used by new .NET managed applications.

My question is simply can a managed DLL written in C++ (or C# for that matter) under .NET be used by traditional VC6.0 MFC applications as well as new .NET web form applications? If so how does one setup the DLL to do this?

- stub

Re: Managed DLL with unmanaged MFC application

Nathan Blomquist11-Jul-03 5:31

Nathan Blomquist

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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Re: Managed DLL with unmanaged MFC application

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

jspano

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

Re: Managed strings and buffers to nonmanaged

Nathan Blomquist10-Jul-03 8:32

Nathan Blomquist

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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Re: Managed strings and buffers to nonmanaged

jspano11-Jul-03 3:23

jspano

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 />

Re: Managed strings and buffers to nonmanaged

Nathan Blomquist11-Jul-03 4:25

Nathan Blomquist

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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