reading multiple times from same stream in c#

Question

hi i want to read the output of my program multiple times. Some thing like if i pass X i get the output and i display it, then again if i pass Y i get the output and i display it. without restarting the process. to try it i have made a c program

#include<stdio.h>
int main()
{
    int i;
    int j;
while(scanf("%d", &i))
{
    for(j = 0; j<=i;j++)
    printf("%d\n",j);
}
return 0;
}

and now i'm interfacting it with C#, where when i enter a text in the textbox it is passed through the redirect standardinput (a streamwriter) to the program and to read the output i call it's standardoutput (a streamreader).readtoend().

But it is not working for me. As it goes in waitstate till the stream returns some indication telling end has been read.

How can i achieve such a thing?

I tried the asynchronous read too where i call the beginoutputread method, but then i won't know when the read has been finished! One way can be for me to add a marker in my original program to indicate that output is over for the current input. Is there any other way for me to achieve it?

Answer 1

If the stream supports seeking (CanSeek), you can "rewind" it by setting

stream.Position = 0;

thus starting to read it all over again.

Answer 2

Quck and Dirty: This one works with some minor glitches. Try improving it, because I'm leaving office :)

        ProcessStartInfo psi = new ProcessStartInfo(@"c:\temp\testC.exe");
        psi.CreateNoWindow = true;
        psi.RedirectStandardError = true;
        psi.RedirectStandardInput = true;
        psi.RedirectStandardOutput = true;
        psi.UseShellExecute = false;

        Process p = Process.Start(psi);
        string input = "";

        ConsoleColor fc = Console.ForegroundColor;

        StreamWriter sw = p.StandardInput;
        StreamReader sr = p.StandardOutput;

        char[] buffer = new char[1024];
        int l = 0;

        do
        {
            Console.Write("Enter input: ");
            input = Console.ReadLine();

            int i = Convert.ToInt32(input);

            sw.Write(i);
            sw.Write(sw.NewLine);

            Console.ForegroundColor = ConsoleColor.Yellow;

            Console.Write(">> ");

            l = sr.Read(buffer, 0, buffer.Length);

            for (int n = 0; n < l; n++)
                Console.Write(buffer[n] + " ");

            Console.WriteLine();

            Console.ForegroundColor = fc;
        } while (input != "10");

        Console.WriteLine("Excution Finished. Press Enter to close.");
        Console.ReadLine();
        p.Close();

PS:- I've created console exe in vs2008 and copied it to c:\temp folder under name testC.exe.

Answer 3

If the stream does not support seeking but the data in stream is not so big, you can read and write that stream to MemoryStream, and read from MemoryStream as many times as you want.

Answer 4

Hi, I try this app and dont work correctly because the app do not write any result(permanent stand alone), please tell me the answer.