Write file in C#

    using System;

    using System.IO;

    class FileWrite

    {

        public void WriteData()

        {

            FileStream fs = new FileStream(@"C:\Test Folder\test.txt", FileMode.Open, FileAccess.Write);

            StreamWriter sw = new StreamWriter(fs);

            string str = Console.ReadLine();

            sw.WriteLine(str);

            sw.Flush();

            sw.Close();

            fs.Close();

        }

        public static void Main(String[] args)

        {

            FileWrite fw = new FileWrite();

            fw.WriteData();

            Console.ReadLine();

        }

    }