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I do not flame others, so you'll have to get your heat elsewhere 
Managed C++ is essentially an extension to the .Net framework stuff (the Common Language Runtime, etc.), in C++ syntax. It is possible to put regular C++ and MC++ in the same project (even the same file). MC++ exposes the same runtime library as all other CLR-based languages, such as C#. Thus, much of the difference between MC++ and C#, is that MC++ exposes the existence of pointers, and C# calls them "reference objects" and bypasses the pointer syntax.
Picking up C# with a C++ background is really easy, and even easier if you have experience with Java. Several new keywords, but most of the stuff is the same. I cannot call using MC++ really changing, as it's more adapting to using some CLR library objects in a familiar syntax. Any class you define as a __gc class, you can use CLR objects in. There is no MFC, ATL, or Win32 API directly in the CLR itself, though you can write wrapper declarations around external DLL functions, and call them from within any .Net code. The CLR is comprehensive, so you won't often have to anyway.
Performance wise, there is little difference between the CLR-base languages, though MC++ allows integration with regular C++, which Microsoft freely admits will remain the speed demon for many things. Well, COM objects still suffer weight problems and circular references, and traditional heap allocation is not as fast as .Net's garbage collected (GC) heap. .Net objects are lightweight and 'new' allocation is really fast, although low-level manipulation is harder with .Net. However, it is possible in C# (research the unsafe and fixed keywords), and MC++ has the best access, although pinning GC memory (keeping it from moving) has a slight penalty. Thus, MC++ has some advantages, but C# is the cleanest syntax.
Some main benefits to CLR-based stuff is rapid development, greater platform independence, a good GUI designer, a good security model, web integration, and the like. Considering such a wide scope, the performance is pretty good, but not higher performance overall than C++. The CLR languages do not replace C++, they are simply better suited to certain tasks and projects.
Naturally, I expect to be flamed as well. Anyone can find an excuse to argue. If every man who's been put on fire stays warm for the rest of his life, then call me Mr. Toasty...
Cheers
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Jeff J wrote:
If every man who's been put on fire stays warm for the rest of his life, then call me Mr. Toasty...
lol!
But seriously, I am exploring the same origional question. Nicely put.
- Nitron
"Those that say a task is impossible shouldn't interrupt the ones who are doing it." - Chinese Proverb
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Thank you,
That was very imformative and very helpful. It gives me a good basis on what the differences are and where to start learning. I am very interested in picking up additional knowledge so I am glad people are willing to share, especially since nobody at work is available to discuss things with. The benefits of the very small company work place may be appealing but there are disadvantages to knowledge growth.
Anyway thanks again, I really appreciate it.
Brian
If you start a fire for a man, he will be warm for a day. If you start that same man on fire, he will be warm for the rest of his life.
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First off I would like to point out that Jeff did an excellent job covering the main jist of the languages, as you asked a very important question. Here are a few links to review that may help:
Here is a nice analysis between I whole slew of Microsoft languages, both managed and not:
A statistical analysis of the performance variations of assorted managed and unmanaged languages[^]
SanShou wrote:
which of the three new language technologies are worth it: Unmanaged C++, Managed C++, or C#?
SanShou wrote:
I already want to learn XML
The best way for me to answer this is to say that you don't have to particularly learn only one of the languages, they work together almost flawlessly. Take a look at my most recent article to point this out:
Cross Language Web Service Implementation[^]
Hope this helps.
Nick Parker
Not everything that can be counted counts, and not everything that counts can be counted. - Albert Einstein
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Thanks.
Yes it did help. Those articles were very interesting and provided a good look in to the architecture and the speeds, not that most of my code is tightly looped for optimization myself, but it was defitinely enlightening. Of course I also need to read them more thorougly when I get a chance.
They also pointed to a few new buzz words and technologies I am going to have to reasearch such as ngen'd. However that is the fun in trying to catch up and learn new things... 
Thanks,
Brian
If you start a fire for a man, he will be warm for a day. If you start that same man on fire, he will be warm for the rest of his life.
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SanShou wrote:
I am going to have to reasearch such as ngen'd
In short, when you load a application that was developed under .NET it has to take the MSIL and run it through the JIT compiler to produce native code in memory. This is typically very fast and you really don't notice it. However there are times when you can use the n'gen utility to run the .NET application through the JIT compiler and have it produce the native code which you can persist to disk. Once the application has been n'gened you will no longer have the JIT compiling taking place, that is essentially all you gain/lose. Hope this helps.
Nick Parker
Not everything that can be counted counts, and not everything that counts can be counted. - Albert Einstein
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Im trying to create a Managed C++ object that will be accessible both from Managed Code, as well as through a standard COM interface. I have written the component and have no problems using it from JScript, so I moved on to attempting use through standard COM from Win32 App. When I export the type library from the assembly, it contains the definitions for the classes but not the interfaces?? For example if I built the following overly simplified managed code into an assembly
<br />
#include "stdafx.h"<br />
<br />
#using <mscorlib.dll><br />
<br />
using namespace System;<br />
using namespace System::Reflection;<br />
using namespace System::Runtime::InteropServices;<br />
<br />
[assembly:AssemblyKeyFileAttribute("ComponentTest.snk")];<br />
<br />
namespace TestNM<br />
{<br />
__gc __interface ITestComp<br />
{<br />
int GetNumber();<br />
void SetNumber(int num);<br />
};<br />
<br />
__gc public class MyTestComp : public ITestComp<br />
{<br />
public:<br />
MyTestComp() { m_iNumber = 0; }<br />
~MyTestComp() {};<br />
<br />
int GetNumber() {return m_iNumber; }<br />
void SetNumber(int num) { m_iNumber = num; }<br />
private:<br />
int m_iNumber;<br />
};<br />
}<br />
Then export the type library, and open with oleview, the definition of "ITestComp" interface is no where to be found, in fact it says MyTestComp is an interface??? Anyone have any ideas?
Thanks!
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Hi tlemoine,
You are right because MyTestComp IS an interface too!, what you need to do is tell the type library exporter that it shouldn't create a type library section for MyTestComp.
You need to add the following attribute...
<ClassInterface(ClassInterfaceType.None)>
can't remember the exact syntax for MC++ though.
Regards,
Dark Angel
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Here is the attribute again.... but visible this time
<ClassInterface(ClassInterfaceType.None)>
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I have a class having overloaded friend operators
<br />
class FpDate<br />
{<br />
friend bool operator < (const FpDate & fpDate1,const FpDate & fpDate2 );<br />
friend bool operator <= (const FpDate & fpDate1,const FpDate & fpDate2 );<br />
friend bool operator == (const FpDate & fpDate1,const FpDate & fpDate2 );<br />
};<br />
<br />
bool operator <= (const FpDate & fpDate1,const FpDate & fpDate2 )<br />
{<br />
return ( (fpDate1 < fpDate2) || <br />
(fpDate1 == fpDate2)<br />
);<br />
}<br />
It is ginving compilation error for both < and == operator call in <= body(above)
What can be the problem?
Thank You
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Could you please show us a sample of where you are calling those operators?
Best regards,
Alexandru Savescu
P.S. Interested in art? Visit this!
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One call is there in the <= operator.
Other is
<br />
const FpDate& rFpDateOperand1<br />
= (GetDateEvaluationValue(uliRecordNumber,<br />
ComparisonExpression::OPERAND_LEFT_SIDE,0));<br />
<br />
const FpDate& rFpDateOperand2<br />
= (GetDateEvaluationValue(uliRecordNumber,<br />
ComparisonExpression::OPERAND_RIGHT_SIDE,0));<br />
return (rFpDateOperand1 > rFpDateOperand2);<br />
Thank You
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I am trying to determine if there is any way other than calling Show(), to force the creation of a handle for a form (or any control, for that matter). I have tried calling CreateControl(), which the docs claim will force handle creation (I presume it wraps to CreateWindowEx()), but no dice.
I need to alter some things before the form becomes visible, which are not just initialisation parameters like text and styles. That is, call control methods which require a handle to exist.
No matter how many CPU cycles pass, CreateWindow() simply returns and no handle ever gets created. Anyone have suggestions?
RSVP
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Have you tried NativeWindow.CreateHandle
Cheers
Kannan
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Thanks Kannan, that was a great idea. I was able to use my form's CreateParams to create a handle with the method you posted. Unfortunately, there does not seem to be a viable way to get a CLR form to attach to the created handle as in MFC/ATL, so I'm left with a raw window without child controls, which knows nothing of CLR stuff.
However, while subclassing I realised I could access the protected CreateHandle(), so I created a public method to call it externally. That worked, however it does not force handle creation for any of the child controls (as CreateControl() is supposed to), so I would have to subclass every one to create them too!
This is an aggravating bug, since non-visible form creation is simple in C/C++, and CreateControl() is supposed to do this too. I remain open to further ideas, and will report this bug to Microsoft (though I'm sure they've heard this one before).
Cheers
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Hi all. I'm a new C++ programmer. Wonder if anyone know how to draw a tree graph with C++? without calling packaged libraries.
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Hello,
I can't change the small icon from the Main Form with the following code in my project:
this->Icon = new System::Drawing::Icon("SAVE.BMP");
With this pice of code i get the following exception error
Unhandled Exception: System.ArgumentException: The argument 'picture' must be a picture that can be used as a Icon.
The same picture is working perfect if i use it for a menubar icon.
Many thanks for a good anwser
Peter.
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Apparently, a System::Drawing::Icon can only be created from an .ico file, and not a .bmp file. There do not seem to be any Icon constructors that take a bitmap. I do not know how you managed it for your menubar icon.
Perhaps the easiest solution would be to copy the bitmap to an .ico file (via resource editor or other), then use the method you posted. Of course, with an .ico you could just set the form's icon from the propery settings, if you are integrated with C#. If you are purely MC++, I suppose you would have jump through a few hoops to compile the icon into a raw resource, and link it in to your executable. Supposedly VS.Net 2003 will make that ea$ier.
If you are mainly interested in converting a bitmap file to an Icon, you could alternatively do:
Bitmap *bmp = new Bitmap("MyIcon.bmp");<br />
this->Icon = Icon::FromHandle(bmp->GetHicon());
or...
Icon *ico = Icon::FromHandle(new Bitmap("MyIcon.bmp"));
Cheers
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Both answers work Perfect )
I have used for the MenuBar a Image List,
I guess it was wrong thinking that a 'ico' file is a renamed
Bitmap file !!
Peter.
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Hi!
I have a structure defined in my old unmanaged class, which is a output parameter of one of my methods. I want to create a managed C++ class which "wrappes" my old one.... the question is:
Which Marshall Type Conversion must I use in order to pass the information of this structure to my managed class and viceversa?
CODE
----------------------------------------------------------------------------------
void Extract( Feature* *MyFeature);
----------------------------------------------------------------------------------
Feature is the structure which is really the output of my method...
Thanks in advance!!!
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Hello,
I'm sorry for bothering the members of the list but I really in need of some help from you guys. Actually I was involved in converting a C++ application (which was developed in MS VC++5) environment into a web service. I ported my application (infact a small version of the
actual application) to VC++.Net and it was working
fine in this environment. Just to make a point that I was
using Objectivity/DB (an OODB) on the backend so I've
to include its libs and headers in my code.
My idea was to convert my apllication in to a managed
C++ application and then to further convert it into a
web service. In order to make it a managed application
I complied my application with the "clr" option and
got some comiplation errors which later I sorted out with some efforts. But now I'm getting linker errors.
First of all, I need some comments from the members on the following questions.
Questions;
=========
1) Is VC++.Net mature enough to be selected for this
kind of problems?
2) Can I also use C# instead of VC++.Net in the above
mentioned scenario?
3) Can you help me in the present linking problem?
The source code is attached and following is the error
ecountered while linking the code.
Linking...
dbconnect.obj : error LNK2001: unresolved external
symbol "void __cdecl os_throw_length_error(void)"
(?os_throw_length_error@@$$FYAXXZ)
manDB.obj : error LNK2001: unresolved external symbol
"void __cdecl os_throw_length_error(void)"
(?os_throw_length_error@@$$FYAXXZ)
.\Debug/newTest.exe : fatal error LNK1120: 1
unresolved externals
Please see the code.......
NB. "dbconnect.h" & "dbconnect.cpp" are the actual
files used in VC5/6 env. whereas "manDB.h" and
manDB.cpp" are the wrappers for managed C++
extensions. Also note that i'm just trying to connect
to Objectivity/DB database.
----------------------------------------------------
dbconnect.h
-----------
//Objectivity/DB headers
#include <ooas.h>
class dbconnect
{
public:
dbconnect();
void start_transaction();
~dbconnect();
private:
ooTrans trans;
};
dbconnect.cpp
-------------
#include "dbconnect.h"
#include <iostream.h>
dbconnect::dbconnect()
{
ooInit();
}
void dbconnect::start_transaction()
{
trans.start();
cout << "Transaction started" << endl;
}
dbconnect::~dbconnect()
{
trans.commit();
cout << "destructor called" << endl;
}
manDB.h
-------
#include "dbconnect.h"
#using <mscorlib.dll>
using namespace System;
public __gc class Mclass
{
public:
Mclass();
~Mclass();
void m_start();
private:
dbconnect * m_pC;
};
manDB.cpp
---------
#include "manDB.h"
Mclass::Mclass()
{
m_pC = new dbconnect();
}
Mclass::~Mclass()
{
delete m_pC;
}
void Mclass::m_start()
{
m_pC->start_transaction();
}
void main()
{
Mclass * d;
d->m_start();
}
Thanks in advance for your co-operation/help.
Cheers,
M. Waseem Hassan
waseem
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I am trying to write a managed C++ extension to be used with a project I am working on. All seems to work well except that .NET seems to refuse to recognize any fstream members, and I can't instantiate it. I include it in the stdafx.h. Any help would be greatly appreciated.
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This should work fine - in my simple test I #include <fstream>, then instantiate a fstream object.
The types defined in fstream are in the std namespace. Does your code reflect this?
#include "stdafx.h"
#using <mscorlib.dll>
#include <tchar.h>
#include <fstream>
using namespace System;
int _tmain(void)
{
std::fstream fs;
fs.open("filename");
Console::WriteLine(S"Hello World");
return 0;
}
This posting is provided “AS IS” with no warranties, and confers no rights. You assume all risk for your use. © 2002 Microsoft Corporation. All rights reserved.
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Your code seems to work however, I am unsure of what file for the #using, I have tried the name of the built .dll in my case Test.dll, but I get the error "Could not find assembly Test.dll". Also if I include no filename, it expects one. I am new to Visual C++ .NET Managed Forums, and I would like to thank you for your patience.
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Anonymous wrote:
I am unsure of what file for the #using
Nick didn't format it (;P), the following will need to be included for the source to work:
#include "stdafx.h"
#using <mscorlib.dll>
#include <tchar.h>
#include <fstream>
using namespace System;
Nick Parker
May your glass be ever full.
May the roof over your head be always strong.
And may you be in heaven half an hour before the devil knows you’re dead. - Irish Blessing
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