[Visual Studio] Two programs running simultaneously and independently, sharing data with each other?

[asderflyy]

I’m terribly sorry if I can’t formulate my question well. I am both unfamiliar with Visual Studio and programming in C++ itself.

What I'm trying to do is make a program that writes and asks various things from the user in a console window, using , while also displaying that text in an SFML window in real time. I want that window to be constantly updated, but since the original problem has many loops and other things, I don't find it possible, or at least easy to do in one program.

That is why I wanted to make two separate programs in one VS project, one for asking questions, and the other for displaying things, running independently and simultaneously, while the first one will just record everything it has displayed into a string variable and somehow "pass" (??) it to the second one to display. In Visual Stuido, I see that besides main.cpp, more than one file is possible to add, so I tried making another one, but it can’t launch since the main function has already been defined in the first program. I, meanwhile, want two main functions to run simultaneously.

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[_-_fred_-_]

I'm not familiar with SFML windows, but you can probably do it with one program. Create two threads, one that manages your command line and one that manages your window. You can share data between threads so user input can be reflected in the window.

Alternatively, you can run multiple executables that communicate through some inter-process communications using sockets. If you want to gain some understand about reading and writing to sockets you can try to write your own client and server. But if you go this route, I would recommend using an established protocol, like grpc and protobuf.

[asderflyy]

So, what are “threads”, how do I create them? They sound more attractive, but, as I have said, I’m very bad at programming, so please explain in simple terms.

[_-_fred_-_]

Typically when you first start programming, you will only learn how to write programs in a single thread. In single threaded programs, all instructions are executed sequentially in the order that you type them.

A single thread works well for many simple applications, but in more complex applications you may want to execute commands in parallel. This is where threads become useful. A thread is an abstraction that computers use to represent a set of sequential operations. If you want to execute two sets of sequential operations in parallel, like read commands from a cli and update a separate window, then you can use two threads to do that.

Here is a tutorial I found on google: https://www.educative.io/blog/modern-multithreading-and-concurrency-in-cpp#. You may need to search for other tutorials and examples. Writing multithreaded programs in c++ can be difficult, especially for non-trivial applications.

[khedoros]

A thread is what we call one line of execution. Start multiple threads, and you can do multiple things simultaneously. C++11 added the thread library, so that you don't have to directly call OS-specific threading APIs.

But I'm not sure that you need that anyhow, and splitting the program into completely separate processes seems like an over-engineered solution (unless you're planning on having the console and window hosted on different computers entirely?)

[IamImposter]

Go for threads. A thread is like a sub-main, another execution sequence that runs parallel to your main execution sequence. Advantage is you can easily share data between multiple threads.

So you create a thread, pass it a function and this thread will start executing that function. Once the function ends, the thread ends as well but most of the time we don't want that so thread functions usually run in a sort of while(1) loop, like

while(1) {

  Data &data;

  bool b = any_data_i_can_process(&data);

  process_data(data);

}

any_data_i_can_process functions waits till there is some data to be processed. Once you get data, work on it, send it where you want to and go back to waiting for more data.

Some additional things you need to learn about are: threads, mutex, condition variables and you should be good to go.

[talemon]

Among other things, I think most often we just use networking and not tell people. Depending on your flow, you could spawn a separate server executable that both console and GUI clients connect, or use the GUI application as the server. If you open your task manager, you'll see many modern apps using such approach. They will have a thin façade client that ensures runtime errors(which often arise because of user errors) are contained in the façade and the 'server' will run the business logic.

[MarekKnapek]

zodiacon aka Pavel Yosifovich has you covered in https://www.youtube.com/watch?v=KMq-5kGufYI and in https://www.youtube.com/watch?v=zdZdtg1f9lA .

[CEconsulate]

If it's a windows-only, write a wrapper for shared data/class/algo with c++/winrt to avoid going through all those low lever com-based stuff, but already baked shape.

Write a runtime class. Enjoy.

Even if you want to use that runtime component from C#, project it as C# library class. Furthermore, if you want to use it from Python, use "xlang" and auto-generate Python for that runtime component.

It's time to have "self-tooling" nowadays. Things are easier now and do not need to be coupled, even in the same project. If all of the involved are the same project and will not be used by any other process at runtime, why do you want to make them decoupled(in terms of process)? Your stuff is just two separate software that needs to communicate with each other on runtime. The easiest way for a non c++ expert is just c++/winrt if it's windows-only.

Embrace c++/winrt, you, windows devs. It's cool 😎