.NET Framework Standard Library Annotated Reference, Volume 1: Base Class Library and Extended Numerics Library

Example

using System;
using System.IO;

namespace Samples
{
  public class FileShareSample
  {
    public static void Main()
    {
      string s = @"open.txt";
      FileShare[] fileShares = { FileShare.None,
                          FileShare.Read,
                          FileShare.ReadWrite,
                          FileShare.Write};
      foreach(FileShare fs in fileShares)
      {
        using(FileStream a = File.Open(s,
                                       FileMode.OpenOrCreate,
                                       FileAccess.ReadWrite,
                                       fs))
        {
          Console.WriteLine("Opened with FileShare: {0}", fs);
          OpenAgain(s);
          Console.WriteLine();
        }
      }
    }
    public static void OpenAgain(string s)
    {
      try
      {
        using(FileStream a = File.Open(s,
                                       FileMode.Open,
                                       FileAccess.Read,
                                       FileShare.ReadWrite))
        {
          Console.WriteLine("Can open file again to read");
        }
      }
      catch(Exception)
      {
        Console.WriteLine("Can not open file again to read");
      }
    }
  }
}

The output is

 Opened ...