Question

I have a GUI application within which i’m spawning a console application using Process class.

Process p1 = new Process(); p1.StartInfo.WindowStyle = ProcessWindowStyle.Hidden; p1.StartInfo.CreateNoWindow = true; p1.StartInfo.UseShellExecute = false; p1.StartInfo.FileName = Path.Combine(basepath, 'abc.exe'); p1.StartInfo.Arguments = '/pn abc.exe /f \'temp1.txt\''; p1.StartInfo.RedirectStandardError = true; p1.StartInfo.RedirectStandardInput = true; p1.StartInfo.RedirectStandardOutput = true; p1.OutputDataReceived += new DataReceivedEventHandler(outputreceived); p1.ErrorDataReceived += new DataReceivedEventHandler(errorreceived); p1.Start(); tocmd = p1.StandardInput; p1.BeginOutputReadLine(); p1.BeginErrorReadLine(); 

Now i have a problem that, though it reads the console output asynchronously but it seems to fire the event only when the internal buffer is filled with some amount. I want it to display data as it comes. If there’s 10 bytes in buffer, let it display the 10 bytes. My program implements sleep() call internally, so i need to print the data till it goes to sleep.

How can i do it?

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As it was mentioned the output is line buffered, i tried the following change in the code

p1.StartInfo.WindowStyle = ProcessWindowStyle.Hidden; p1.StartInfo.CreateNoWindow = true; p1.StartInfo.UseShellExecute = false; p1.StartInfo.FileName = Path.Combine(basepath, 'abc.exe'); p1.StartInfo.Arguments = pnswitch + ' /f \'temp1.txt\''; p1.StartInfo.RedirectStandardError = false; p1.StartInfo.RedirectStandardInput = true; p1.StartInfo.RedirectStandardOutput = true; p1.Start(); tocmd = p1.StandardInput; MethodInvoker mi = new MethodInvoker(readout); mi.BeginInvoke(null, p1); 

and inside readout i wrote

void readout()     {         string str;         while ((str = p1.StandardOutput.ReadLine()) != null)         {             richTextBox1.Invoke(new UpdateOutputCallback(this.updateoutput), new object[] { str });             p1.StandardOutput.BaseStream.Flush();         }     } 

So i think it now monitors when each line is written and it prints it right? this too didn’t work. Any thing wrong there?

Answer 1

The Output and Error Data received is line buffered, and will only fire when a newline is added.

Your best bet is to use you own reader that can read the input, byte by byte. Obvioulsly, this would have to be non-blocking 🙂