Console.OpenStandardError Method in C#

Last Updated : 06 May, 2019

This method is used to acquire a standard error stream. This method can be used to reacquire the standard error stream after it has been changed by the SetError method. Syntax:

public static System.IO.Stream OpenStandardError ();

Returns: This method returns the standard error stream. Example: The below code first checks for the string to be GeeksForGeeks and if not so then the program calls the SetError method to redirect error information to a file, calls the OpenStandardError method in the process of reacquiring the standard error stream, and indicates that error information was written to a file. The StreamWriter.AutoFlush property is set to true before reacquiring the error stream. This ensures that output will be sent to the console immediately rather than buffered.

csharp

// C# program to illustrate the 
// OpenStandardError() Method
using System;
using System.IO;

namespace GeeksforGeeks {

class GFG {


    // Main Method
    static void Main(string[] args)
    {
        Console.WriteLine("Please Write GeeksForGeeks");
        string a;
        a = Console.ReadLine();

        // checks for a string to be GeeksforGeeks
        if (!a.Equals("GeeksForGeeks")) { 

            // Write error information to a file.
            Console.SetError(new StreamWriter(@".\Errorfile.txt"));

            Console.Error.WriteLine("The String is not GeeksForGeeks");
            Console.Error.Close();

            // Reacquire the standard error stream.
            var standardError = new StreamWriter(Console.OpenStandardError());
            standardError.AutoFlush = true;

            Console.SetError(standardError);

            Console.Error.WriteLine("\nError information written"+
                                             " to Errorfile.txt");
        }
    }
}
}