FileStream

[kenobe]

Hi
I have created a VC++.net MFC dialogbased application.
I need to save some data to a binary file.

my code is as follow


using namespace System;
using namespace System.IO;
using namespace System.Text;
using namespace System.IO.Stream;
:
:
:
void CfileReadWriteDlg::OnBnClickedSave()
{ CString infoFile ;
infoFile = "studentInfo.dat";
// TODO: Add your control notification handler code here
FileStream *fs = new FileStream(infoFile,FileMode::Create);
StreamWriter *swfs = new StreamWriter(fs);

swfs->WriteLine("This is a test");
swfs->Flush();
swfs->close();
Close();

}


when I run build solution , I got the following errors

error C2065: 'FileStream' : undeclared identifier
error C2065: 'fs' : undeclared identifier
error C2061: syntax error : identifier 'FileStream'
error C2653: 'FileMode' : is not a class or namespace name
error C2065: 'StreamWriter' : undeclared identifier
error C2065: 'swfs' : undeclared identifier
::
::

Why am I getting this errors, did I miss something? or
FileStream is only for C# and cannot be used in VC++.net?

Thanks

[Ejaz]

[ Redirected Thread ]

[cilu]

Well, I guess you mean:

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::IO::Stream;

[kenobe]

I did tried


using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::IO::Stream;

but still same errors!

[darwen]

I think the key here is in the line of the question :


VC++.net MFC dialogbased


You're mixing managed and unmanaged code ! MFC-based applications are native, not managed so you don't have access to the .NET functionality unless you tell is so.

I'd create a WinForms application if I were you (managed windows application or whatever).

Or create an MFC application and stick to native C++ code (i.e. use the MFC file classes like CFile, CArchive etc).

Don't try to mix the two unless your absolutely certain about what you're doing.

Darwen.

[cilu]

I think the key here is in the line of the question :

VC++.net MFC dialogbased

Ah. Good point. Somehow I missed that... ;)

[kenobe]

Hi darwen
I think you are right, but you said

so you don't have access to the .NET functionality unless you tell is so.


So, how could I do it? how do I tell the IDE that I need to acess to the .NET functionality?

Thanks

[cilu]

You must use the /clr command option.

To set this compiler option:

Open the project's Property Pages dialog box.
Click the Configuration Properties folder.
Click the General property page.
Modify the Use Managed Extensions property.

[NoHero]

You must use the /clr command option.

To set this compiler option:

Open the project's Property Pages dialog box.
Click the Configuration Properties folder.
Click the General property page.
Modify the Use Managed Extensions property.


Or use the #pragma directive:

// Unmanaged code

#pragma managed

// Managed code

#pragma unmanaged

[darwen]

To say what I said before I don't think you should be mixing managed and native code in this way : you should stick to one or the other.

There's no need to write a dialog based MFC app using .NET underneath when you can just write a winforms application instead.

You only mix the two when necessary : if it's unnecessary you'll soon start asking questions like "how do I convert a LPCSTR to a String ^" etc etc when there's no need.

Please just stick to one or the other. Or be prepared for headaches aplenty.

Darwen.

[kenobe]

Hi Darwen
I understand your point and agree to it fully.
But this is the assignment given to me to write a student attendance system using .NET.

I choose dialogbased application so that I can capture the user input easily.


Come back to the problem, I apply the change to YES as suggested by
you

To set this compiler option:
Open the project's Property Pages dialog box.
Click the Configuration Properties folder.
Click the General property page.
Modify the Use Managed Extensions property.


Yet I still have the same error

I hope I am not too naive to understand your advise

[darwen]

You're still not getting it are you ? Write a WinForms app : this'll do all the UI in managed code, not native. There will be a wizard to do this in VS2003. There's not in VS2002, but there is in VS2003.

Personally if I'd stated


But this is the assignment given to me to write a student attendance system using .NET.


in a question I wrote and someone handed in an MFC application I'd mark them down because they wouldn't have produced what I'd asked for. If this happened in my company I would get you to write it again : period.

Darwen.

[kenobe]

Hi Darwen
I appreciate and understand your advise.
But if I switch to WinForms app, it means that I have to rewrite the project all over again starting from zero.
But if this is the only choice, then I need to do it and I have to pay the price of not selecting the correct .net application type initially.

Thanks

[darwen]

Hopefully you've designed your application nicely and all the functionality will be in portable classes which you can transfer over.

If not, I'd strongly recommend you do it again. Mixing MFC and .NET like this isn't advisable : in a commercial environment it would make the MFC application dependent on the .NET framework being installed on the target machine. One of the reasons for writing native code is to remove this dependency.

Chalk it up to experience and get on with it : you'll find that you'll end up rewriting a lot of code when learning a new language - it's just part and parcel of learning how not to do things.

Darwen.

[kenobe]

Hi
Darwen
I will take your advise and note it in my diary .
Thank you very much, appreciated.

Thanks