MFC or .NET FCL?

[Guest]

I am porting an application from older tools to .NET FCL or MFC. The
application has over two million lines of code that will be moved over. Most
of the code sends low level commands to disk drives and handles responses,
with a user interface comprising the rest of the code. The new application
will essentially be the old code running with a new GUI. The reasons for
rewriting this is to improve performance and usability.

Question: Should I use .NET Framework Class Libraries, or MFC? I would
like to use .NET, but am afraid that my older, unmanaged code will need to be
run in one environment, and the new managed code needs to run in another
environment (in the CLR) and switching between them will kill performance.
If I use MFC, I don't think I'll have the performance hit.

Can you help me understand these issues better, and give me suggestions,
which way is best?

 

[Rodrigo Corral [MVP]]

C++/CLI was designed for the kind of task that you have in your hands. The
performance hit exist but it is small if you make a good design of your
application, with especial attention from managed to unmanaged transitions,
trying to minimize them.

Here there is an article that could be interesting for you:
http://msdn.microsoft.com/msdnmag/issues/05/01/COptimizations/default.aspx

 

[Guest]

Thank you. That did help (and the suggested web site was helpful), but
brought on a couple of other questions.
1. I know this depends on the app, but how much faster is unmanaged code
vs. managed code?
2. Is it as simple as using a #pragma to convert from unmanaged to managed?
And if so, can I simply change my existing code to managed with the #pragma
wherever I want to eliminate transitions, or are there issues with this?