[.net] C#: Launching another process and capturing stdout
Author
Hey,
I'm trying to use C# to make a GUI front-end for some C++ command-line apps I have, but my C# knowledge is next to none, so I'm trying to find some examples on the web that do what I need. I got everything working, I just can't capture the output and display it in real-time.
In my test app, I produce about one line of text every second for 5 seconds. In every method I've seen, the C# app simply spits out all the text 5 seconds later.
Does anyone know how I can capture the input in real-time and display it into a text-box?
[Edited by - gekko on January 19, 2009 3:47:05 PM]
Author
Unfortunately, no. I'm making a GUI wrapper in C#, and trying to launch a C++ console app, so I'm using System.Diagnostics.Process to do so.
As I said before, this is working for me, but it outputs all the captured output at once when the console app finishes. I want it to capture every time there is a write to the console from the C++ app, it captures it and updates the text box.
private void exportButton_Click(object sender, EventArgs e) { System.Diagnostics.Process p = new System.Diagnostics.Process(); p.StartInfo.FileName = "ModelExporter.exe"; p.StartInfo.Arguments = ""; p.StartInfo.RedirectStandardOutput = true; p.StartInfo.RedirectStandardInput = true; p.StartInfo.UseShellExecute = false; p.StartInfo.CreateNoWindow = true; p.OutputDataReceived += new System.Diagnostics.DataReceivedEventHandler(ConsoleOutputHandler); p.Start(); p.BeginOutputReadLine(); //p.WaitForExit(); //p.Dispose(); } private void UpdateTextBox(String message) { if (consoleOutputBox.InvokeRequired) { UpdateConsoleWindowDelegate update = new UpdateConsoleWindowDelegate(UpdateTextBox); consoleOutputBox.BeginInvoke(update, message); } else { consoleOutputBox.AppendText(message); } } void ConsoleOutputHandler(object sendingProcess, System.Diagnostics.DataReceivedEventArgs recieved) { if (!String.IsNullOrEmpty(recieved.Data)) { UpdateTextBox(recieved.Data + "\n"); } }As I said before, this is working for me, but it outputs all the captured output at once when the console app finishes. I want it to capture every time there is a write to the console from the C++ app, it captures it and updates the text box.
Quote:Original post by gekkop.OutputDataReceived += new System.Diagnostics.DataReceivedEventHandler(ConsoleOutputHandler);
Have you tried using the 'StandardOutput' property instead? I have had good results in the past using a method similar to the below:
System.Diagnostics.Process p = new System.Diagnostics.Process();p.StartInfo.FileName = "ModelExporter.exe";p.StartInfo.RedirectStandardOutput = true;p.StartInfo.RedirectStandardInput = true;p.StartInfo.UseShellExecute = false;p.StartInfo.CreateNoWindow = true;p.Start();StreamReader myStreamReader = p.StandardOutput;// Reads a single line of the programs output.string myString = myStreamReader.ReadLine(); // This would print the string to the DOS Console for the sake of an example.// You could easily set a textbox control to this string instead...Console.WriteLine(myString);p.Close();For more information see:Process.StandardOutput Property.
-Bill
Author
Thanks guys. Apparently, it was working the whole time. Running a console app with more output indeed updates in real-time, but my program outputting only limited amount of data at a slow rate, all got buffered into the same call.
You can make your C++ console app output in realtime by adding the following line to the C++ app
setvbuf( stdout, NULL, _IONBF, 0);This topic is closed to new replies.
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