Reading/Writing to a command line program in c#

Question

I\'m trying to talk to a command-line program from C#. It is a sentiment analyser. It works like this:

CMD> java -jar analyser.jar

>

Answer 1

Here's a little demo showing how to do what you are asking.

This is a toy command line app that just reads from standard input and echos back to standard output:

class Echoer
{
    static void Main(string[] args)
    {
        while (true)
        {
            var input = Console.ReadLine();
            Console.WriteLine("Echoing: " + input);
        }
    }
}

This is another command line app that runs the above app, passing input to it, and reading its output:

class Program
{
    static void Main(string[] args)
    {
        ProcessStartInfo processStartInfo;
        processStartInfo = new ProcessStartInfo();
        processStartInfo.CreateNoWindow = true;

        // Redirect IO to allow us to read and write to it.
        processStartInfo.RedirectStandardOutput = true;
        processStartInfo.RedirectStandardInput = true;
        processStartInfo.UseShellExecute = false;

        processStartInfo.FileName = @"path\to\your\Echoer.exe";

        Process process = new Process();
        process.StartInfo = processStartInfo;
        process.Start();
        int counter = 0;
        while (counter < 10)
        {
            // Write to the process's standard input.
            process.StandardInput.WriteLine(counter.ToString());

            // Read from the process's standard output.
            var output = process.StandardOutput.ReadLine();
            Console.WriteLine("Hosted process said: " + output);
            counter++;
        }

        process.Kill();

        Console.WriteLine("Hit any key to exit.");
        Console.ReadKey();
    }
}

If the app you are hosting does not simply produce a line of output in response to a line of input, then you can look at capturing output asynchronously using Process.BeginOutputReadLine (there's example code in the linked documentation).