CODEWITHSUNDEEP
c#dllprocessstdoutstdin
Ari
Ari

Reputation: 3127

Standard input/output in C# process

My application App is using other my application SubApp. When App needs SubApp it is creating process with SubApp, putting data to SubApp stdin and reading from SubApp stdout.

The problem is that SubApp is using some library which sometimes writes to stdout.

Fragment of SubApp code:

OutsideLibrary.DoSomeInitialization();  // <-- this sometimes writes to stdout
Stream input = Console.OpenStandardInput();
Stream output = Console.OpenStandardOutput();
data = (dataFormat)formatter.Deserialize(input);
//do some job
formatter.Serialize(output, result);

Is there any way to prevent code I don't have from writing to stdout?

Upvotes: 1

Views: 3985

Answers (2)

David Goshadze
David Goshadze

Reputation: 1437

Assuming you want to disable third party component output and you have control over the rest of SubApp code you can do following trick: Redirect standard output to null at application bootstrap. When you need to write something to stdout temporary set standard output back to normal, write and set to null again.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace stdio
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.SetOut(System.IO.TextWriter.Null);
            Console.WriteLine("This will go to > null");
            WriteOutput("This is written to standard output");
            Console.WriteLine("This will also go to > null");
            Console.ReadKey();
        }

        static void WriteOutput(String someString)
        {
            Console.SetOut(Console.Out);
            Stream output = Console.OpenStandardOutput();
            StreamWriter sw = new StreamWriter(output);
            sw.Write(someString);
            sw.Flush();
            sw.Close();
            output.Close();
            Console.SetOut(System.IO.TextWriter.Null);
        }



    }
}

Upvotes: 2

Axel Kemper
Axel Kemper

Reputation: 11324

I've tried this:

StreamWriter sw = new StreamWriter(@"c:\nul");
Console.SetOut(sw);
Console.WriteLine("hello!");

But it throws an exception in new StreamWriter().

The following might work (call it before your external module becomes active):

StreamWriter sw = new StreamWriter(Stream.Null);
Console.SetOut(sw);

A workaround would be to open a real text file and delete it.

Upvotes: 1

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