Csharp/C Sharp/File Stream/UTF8 UTF16

Convert UTF-8 and ASCII encoded bytes back to UTF-16 encoded string

using System;
using System.IO;
using System.Text;
class Test
{
    public static void Main() 
    {        
        using (StreamWriter output = new StreamWriter("practice.txt")) 
        {
            // Create and write a string containing the symbol for Pi.
            string srcString = "Area = \u03A0r^2";
            // Convert the UTF-16 encoded source string to UTF-8 and ASCII.
            byte[] utf8String = Encoding.UTF8.GetBytes(srcString);
            byte[] asciiString = Encoding.ASCII.GetBytes(srcString);
            
            // Write the UTF-8 and ASCII encoded byte arrays. 
            output.WriteLine("UTF-8  Bytes: {0}", BitConverter.ToString(utf8String));
            output.WriteLine("ASCII  Bytes: {0}", BitConverter.ToString(asciiString));
            
            
            // Convert UTF-8 and ASCII encoded bytes back to UTF-16 encoded  
            // string and write.
            output.WriteLine("UTF-8  Text : {0}", Encoding.UTF8.GetString(utf8String));
            output.WriteLine("ASCII  Text : {0}", Encoding.ASCII.GetString(asciiString));
            Console.WriteLine(Encoding.UTF8.GetString(utf8String));
            Console.WriteLine(Encoding.ASCII.GetString(asciiString));
        }
    }
}

UTF8 decoder

using System;
using System.IO;
using System.Text;
class Class1{
  static void Main(string[] args)  {
         byte[] byData = new byte[100];
         char[] charData = new Char[100];
         try {
            FileStream aFile = new FileStream("practice.txt",FileMode.Open);
            aFile.Seek(55,SeekOrigin.Begin);
            aFile.Read(byData,0,100);
         }
         catch(IOException e)
         {
            Console.WriteLine("An IO exception has been thrown!");
            Console.WriteLine(e.ToString());
            Console.ReadLine();
            return;
         }
         Decoder d = Encoding.UTF8.GetDecoder();
         d.GetChars(byData, 0, byData.Length, charData, 0);
         Console.WriteLine(charData);
         return;
  }
}