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.

// 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"); 
        } 
    } 
} 
} 