You can use the Process component to start and stop processes and retrieve information about the processes currently running on your system. We will be using this component to launch a console application, specify startup parameters, and redirect standard input and output. This component exists in the System.Diagnostics namespace.

using System.Diagnostics;

The following code defines a method that launches a redirected console application using the specified file path and argument list. Most of the code is fairly self-explanatory, though we set UseShellExecute to false so Windows Explorer is not used to launch the process. RedirectStandardInput is set to true so that we can get a stream handle to the console output. We also set CreateNoWindow to true so that a command prompt window is not launched alongside our Windows Forms application when the process is started.

The StandardOutput property returns a StreamReader that can retrieve the output data from the console application. The HasExited property can be queried while data is being read from the output stream.

public void LaunchConsoleApplication(string fileName, string arguments)
{
    if (!File.Exists(fileName))
    {
        MessageBox.Show("Invalid path to console application!");
        return;
    }

    Process process = new Process();

    process.StartInfo.FileName = fileName;
    process.StartInfo.UseShellExecute = false;
    process.StartInfo.RedirectStandardOutput = true;
    process.StartInfo.Arguments = arguments;
    process.StartInfo.CreateNoWindow = true;

    process.Start();

    StreamReader reader = process.StandardOutput;

    while (!process.HasExited)
    {
        OuputField.Text += reader.ReadLine() + Environment.NewLine;
        Application.DoEvents();
    }
}

The last piece of important code is to be placed in the closing event of the Form wrapping the console application. This code checks if the process is valid and if it has not exited yet. If true, the process is aborted. Obviously, this event has to have a reference to the process created by LaunchConsoleApplication.

The following code shows this event logic.

private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
    if (_process != null && !_process.HasExited)
    {
        _process.Kill();
    }
}

The example provided alongside the implementation for this chapter is very simple. The demo console application is given two arguments: an iteration count and a message to print. The message is printed out however many iterations are specified.

The following code in the Windows Forms demo makes the console application print “Hello World” out five times. The number of iterations to print the message out is dependent on the iteration count specified as a parameter to the launch method.

private void LaunchButton_Click(object sender, EventArgs e)
{
    string message = ""Hello World"";
    LaunchConsoleApplication("SimpleConsoleApplication.exe",
                             "5 " + message);
}

The following code shows the logic for the demo console application.

static void Main(string[] args)
{
    int count = Convert.ToInt32(args[0]);

    string message;

    if (args[1] != null && args[1].Trim().Length > 0)
        message = args[1];
    else
        message = "No Message";

    for (int index = 0; index < count; index++)
    {
         Console.WriteLine(message + " - # " + (index + 1).ToString());
         System.Threading.Thread.Sleep(300);
    }
}

In this chapter, I discussed how to launch a console application process with parameters and redirect output to a Windows Forms application. This technique is very useful when you want to create a graphical user interface for an already existing console utility, while saving as much development and maintenance time as possible.