Console.SetOut

A console program can write its output to a file. With the Console.SetOut method, we specify a StreamWriter as the output object.

Then, when the program executes, all the Console.Write calls will be printed to the file. We can also use Console.SetIn to adjust the input source.

SetOut example

With this program, we create a new StreamWriter in a using-statement. Then we use the SetOut method and pass the StreamWriter instance to it.

using System;
using System.IO;

class Program
{
    static void Main()
    {
        using (StreamWriter writer = new StreamWriter("C:\\out.txt"))
        {
            Console.SetOut(writer);
            Act();
        }
    }

    static void Act()
    {
        Console.WriteLine("This is Console.WriteLine");
        Console.WriteLine("Thanks for playing!");
    }
}
This is Console.WriteLine
Thanks for playing!

SetIn example

We can also use Console.SetIn to set the input source—we can use to automate calls such as a Console.ReadLine. Streams can be dynamically modified in the .NET Framework.

using System;
using System.IO;

class Program
{
    static void Main()
    {
        using (StreamReader reader = new StreamReader("C:\\programs\\file.txt"))
        {
            Console.SetIn(reader);
            X();
        }
    }

    static void X()
    {
        string line = Console.ReadLine();
        Console.WriteLine("READLINE RETURNED: " + line);
    }
}
HELLO WORLD!
READLINE RETURNED: HELLO WORLD!

We used the Console.SetOut method for changing the target of the output of a console program. We also used SetIn to change the input source.