using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
class Program
{
static void Main(string[] args)
{
FileStream aFile = new FileStream("Temp.txt", FileMode.Create);
char[] charData = "this is a test.".ToCharArray();
byte[] byData = new byte[charData.Length];
Encoder e = Encoding.UTF8.GetEncoder();
e.GetBytes(charData, 0, charData.Length, byData, 0, true);
// Move file pointer to beginning of file.
aFile.Seek(0, SeekOrigin.Begin);
aFile.Write(byData, 0, byData.Length);
}
}