How to send a number from a form in C# to a console program in C++

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I need to run an unmanaged C++ application, this application must be connected to a library in C# (dll which when loading must show a form with a button) and wait for form close event to terminate.

While the form is loaded, at the moment of pressing the button the click event should be executed, which should execute a function that can send a number of return to the console application in C ++ and this application will show the resulting number in the output of the console.

What I need is to solve point 5. shown below, I read a lot of documents but almost all refer to the interoperation between a C++ dll and a C# application and not the reverse (Return an integer value from C# dll to a C++ console application) is what is needed here.

The execution must be dynamic, that is, while the form is displayed, a communication should be established from a function of the C# library and a function of the parent C++ console application.

All the examples that I have been able to find do almost the same, load the libraries, establish the communication and, from the C++ console application they call a function of the C# library and show the resulting return value and the application ends, but no example shows how to load the C# library, show the form, press a button, and send a integer number as a result to the C++ parent console application and show the result in the output of the console.

If you have any idea how to implement the Callback, I would be very grateful.

What I have tried:

What has been achieved is:

1. Load C++ console application (unmanaged), achieved
2. Load a C# library from the C++ console application, achieved
3. Import and communicate with some functions exported from the C# library, achieved
4. When loading the C# library, from this library a form with an button is shown, achieved
5. While the form is displayed, press the button and execute a function in C# that returns an integer to the C++ console application and print the result in the output of the console from the C++ console application, pending

Posted 14-Nov-18 3:41am

fisadmaster

Updated 14-Nov-18 7:51am

v2

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Richard MacCutchan 14-Nov-18 9:46am

This sounds like a lot of work to do something which could most likely be achieved more easily. Why not a C# console app that can communicate more easily with the library? Or a Windows Form app that starts a console app with the relevant number?

fisadmaster 14-Nov-18 9:55am

@Richard MacCutchan, the requirement is established in this way because it needs to perform different operations between an unmanaged C++ application and a library in C# and it is necessary to test the interoperability between languages for future implementations

Richard MacCutchan 14-Nov-18 10:00am

OK, then you need to set an event handler in the library that can call out to the console app. Which most likely will need some C++/CLI code in between.

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Richard MacCutchan · Answer 1 · 2018-11-14T04:04:00

Solution 1

You can find more information about this subject at Native and .NET Interoperability[^].

Posted 14-Nov-18 4:04am

Richard MacCutchan

Comments

fisadmaster 14-Nov-18 10:11am

You are right with C++/CLI code, But, I have already done a lot of examples but they are all of the static type, a call to a function in the C# library and a return value, but no example of how to expect a dynamic response, that is, more once for each execution, like a listener from unmanaged C++

Richard MacCutchan 14-Nov-18 10:19am

I don't know of any other way to do what you want. It may be better to use a message passing service, or look at the possibility of using pipes.

KarstenK · Answer 2 · 2018-11-14T07:52:00

Solution 2

Read my artcle about interoperability to understand the mechanismus.

You may add some additional layer like an addtional thread or some wait mechanismus like semaphores in the C++ app, which waites for the interaction and than runs further.

It sounds a bit weired, I think you really should reconsider the design - if it is possible. ;-)

Posted 14-Nov-18 7:52am

KarstenK

Comments

fisadmaster 14-Nov-18 14:00pm

Thanks for the comment but, I need the opposite of what is described in your article, I need to load a C # dll that shows a form and when clicking the button located in this form, an integer must be sent back to the C ++ application that has loaded the C # library and esdta should show the result in the console (I think it is callback from C ++ to C #).

You import the functions of C ++ to a C # application, I need to react from C # to unmanaged C ++

KarstenK 15-Nov-18 2:39am

try: https://www.codeproject.com/articles/6916/how-to-load-a-dynamic-link-library-dll-into-a-micr

A problem may be that dll arent allowed to show UI.

fisadmaster 15-Nov-18 2:44am

Thanks for the data, but the article is for C++ to C++ not C++ to C#.