Can I use a php file on a server, to send data to a C# file which then validates the data, and sends the result back to the php file?

I'll try to be as simplistic and transparent as I can.
My goal is to: send leaderboard data to a server, have it validated, then added to a MySQL table..

How I want to achieve this:

1. Player completes game, gets highscore data.
2. The highscore data is sent to a file on the server, "leaderboard.php"
3. The leaderboard.php file sends the playthrough data to a C# file on the server, "PlaythroughSimulator.cs" to run a simulation of the playthrough
4. After the PlaythroughSimulator.cs file has confirmed or denied the validity of the playthrough, it sends a true/false value back to the leaderboard.php file
5. If the recording was valid, the leaderboard.php file adds it to the table as expected.

I have the php process working for receiving and adding scores to the leaderboards on the server, and I've created the playthrough simulator in C# OUTSIDE of the server.
My problem now is bringing the playthrough simulator onto the server and making it work entwined with the php script.

I did a bit of reading and see that I should be able to call C# scripts from php, but I'm not sure how to send or retrieve data between them.

Generally speaking, different programs on a computer don't know or care what language each other are written in; they care what protocols they speak - what inputs they expect, what outputs they'll give, and where that information needs to be passed.

For instance, when you have data in the browser and you want to send it to a PHP program, the browser doesn't need to know what PHP is; instead, it sends the data over the internet, using the HTTP protocol. On the server, a process listens for that request, and it just happens that you've set that up so that it runs your PHP script.

In the same way, you won't be telling PHP to "run a C# file"; you'll be telling it to send some data to another program, and that program will happen to be written in C#. An important consequence of this is that it helps you break the problem down, always a key skill in programming, because you can run the program you wrote in C# directly, and confirm how it behaves, before telling PHP to talk to it.

The simplest "protocol" to use in this scenario is a command-line script:

1. Write a C# program that takes the playthrough data as a command-line argument, or reads it from a file, and outputs a result
2. Use shell_exec in your PHP code to run the script, passing it the data, or the name of a temporary file containing the data