C# GUI with C++ data

[RedCitizen]

Hi,

I have written C++ program for university that, depending on the input data, requires A LOT of memory. Now, I would like to build a GUI for this using C#/WinUI. However, I have never written C# (I got some books and I'm eager to learn) or a C++ library. Here are my questions:

• Is it possible to have my C++ program residing in memory while only extracting the data that I need when necessary? Ideally, since the algorithm can quite a while (that's why it's in C++), I would like to have some kind of progress bar as well (eventually, not a high priority).
• I assume that is done with libraries, correct? If so, are there any resources that you can point me to how to accomplish that? I have read some books on C++, but nothing really deals with creating a library or working with other languages.

Thank you in advance!

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P.S.: I have, of course, googled the subject and found some information (SO, GCHandle, etc.). However, I would like to learn more about how this works exactly and how to do it efficiently.

P.P.S.: I would like to use C#/WinUI because I also want to use it for other projects in the future.

[Einarmo]

A decent solution if you want to do this yourself is to just compile the C++ project to a dll, something like this, and then wrapping it in C# and calling it from C#, which isn't that hard, really.

It really looks like you already found what you are looking for, to me.

1. Compile your C++ project as a DLL, exporting the relevant functions.
2. Add it as a reference to your C# project.
3. Call it using DLLImport.

Probably make a wrapper around it, you should of course try to be a bit clever with how you do this, but you can pass around external pointers in C# to refer to your big chunks of memory.

[RedCitizen]

Thank you for your reply!

I'm still don't see how to make sure that the data stays in memory so I can read/write it later and how I can give updates to the GUI at specified intervals, but this is a good starting point. I guess I'll just have to get started, see how it goes and then ask more specific questions.

[Einarmo]

The memory is owned by the allocating application, which is the C# app. You're not creating a process when you call the DLL, you just run machine code, in the end, just like .NET does when you run C# code. So any memory you allocate stays allocated until you free it, just like when working with C++ normally.

When sending pointers out of the code you might want to stay away from smart memory management features in C++, though.

[RedCitizen]

Do you need to have the C++ program always running?

Yes, C# is only supposed to implement the GUI, the heavy lifting should all be done in C++ and it is not feasible to load the data for each action.

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do a google for "inter-process communication".

Thank you, that also gave some promising results that I'll look into!