Streamreader readline returning null value from process execution

Question

I am trying to get the output of the process line by line, but I am getting null value being returned. Can you please check my below code and let me know what wrong am doing here? Please suggest

Process process = new Process();
process.StartInfo.FileName = dirPath + "\\test.exe";
process.StartInfo.Arguments = "-a -h -s " + dir;
process.StartInfo.RedirectStandardOutput = true;
process.StartInfo.UseShellExecute = false;
process.StartInfo.CreateNoWindow = true;
process.Start();

using (StreamReader streamReader = Process.StandardOutput)
{
    string line = streamReader.ReadLine();
    while (line != null)
    {
        Console.WriteLine(line);
    }
}
process.WaitForExit();

If I use string line = streamReader.ReadToEnd() it displays all the lines.

Use a breakpoint in the while, and check if there really is a value in the line? — HEWhoDoesn'tKnow, Dec 11 '18 at 01:57
@HEWhoDoesn'tKnow: It doesnt have any value when i use ReadLine(). — Dhillli4u, Dec 11 '18 at 02:07
Why aren't you waiting for it to exit *before* getting its output? — , Dec 11 '18 at 02:11

Dhillli4u · Answer 1 · 2018-12-11T06:25:08.887

I was able to fix this by making the below changes. I needed to add !streamReader.EndOfStream in the while loop and then parse through each line by line by using streamReader.ReadLine() which worked for me.

                Process process = new Process();
                process.StartInfo.FileName = Pathdir + "\\test.exe";
                process.StartInfo.Arguments = "-a -h -s " + dir;
                process.StartInfo.RedirectStandardOutput = true;
                process.StartInfo.UseShellExecute = false;
                process.StartInfo.CreateNoWindow = true;
                process.Start();

                using (StreamReader streamReader = process.StandardOutput)
                {
                    while (!streamReader.EndOfStream)
                    {
                        string line = streamReader.ReadLine();
                        Console.WriteLine(line);
                    }
                }

If you want to make a suitable answer, explain what you did, just dont paste lumps of code, explain why it is you think it works, add any documentation that backs this up — TheGeneral, Dec 11 '18 at 03:27
@TheGeneral I am trying to learn the coding side and am still in the starting stage. So my current method is based on trial and error method and the inputs you provide. If I am able to explain definitely I will add my points to the data in the future. — Dhillli4u, Dec 11 '18 at 06:11

Streamreader readline returning null value from process execution

1 Answers1