C Method of Reading Files through Pointers

This article illustrates how C # reads a file through a pointer. Share it for your reference. The details are as follows:

// readfile.cs
//  Use at compile time: /unsafe
//  Parameters: readfile.txt
//  Use this program to read and display text files. 
using System;
using System.Runtime.InteropServices;
using System.Text;
class FileReader
{
  const uint GENERIC_READ = 0x80000000;
  const uint OPEN_EXISTING = 3;
  IntPtr handle;
  [DllImport("kernel32", SetLastError=true)]
  static extern unsafe IntPtr CreateFile(
    string FileName,        //  Filename 
    uint DesiredAccess,        //  Access mode 
    uint ShareMode,          //  Shared mode 
    uint SecurityAttributes,    //  Security attribute 
    uint CreationDisposition,    //  How to create 
    uint FlagsAndAttributes,    //  File attributes 
    int hTemplateFile        //  Handle to the template file 
    );
  [DllImport("kernel32", SetLastError=true)]
  static extern unsafe bool ReadFile(
    IntPtr hFile,          //  File handle 
    void* pBuffer,        //  Data buffer 
    int NumberOfBytesToRead,  //  Number of bytes to read 
    int* pNumberOfBytesRead,    //  Number of bytes read 
    int Overlapped        //  Overlapping buffer 
    );
  [DllImport("kernel32", SetLastError=true)]
  static extern unsafe bool CloseHandle(
    IntPtr hObject //  Object handle 
    );
  public bool Open(string FileName)
  {
    //  Open an existing file for reading 
    handle = CreateFile(
      FileName,
      GENERIC_READ,
      0, 
      0, 
      OPEN_EXISTING,
      0,
      0);
    if (handle != IntPtr.Zero)
      return true;
    else
      return false;
  }
  public unsafe int Read(byte[] buffer, int index, int count) 
  {
    int n = 0;
    fixed (byte* p = buffer) 
    {
      if (!ReadFile(handle, p + index, count, &n, 0))
        return 0;
    }
    return n;
  }
  public bool Close()
  {
    //  Close the file handle 
    return CloseHandle(handle);
  }
}
class Test
{
  public static int Main(string[] args)
  {
    if (args.Length != 1)
    {
      Console.WriteLine("Usage : ReadFile <FileName>");
      return 1;
    }
    if (! System.IO.File.Exists(args[0]))
    {
      Console.WriteLine("File " + args[0] + " not found."); 
      return 1;
    }
    byte[] buffer = new byte[128];
    FileReader fr = new FileReader();
    if (fr.Open(args[0]))
    {
      //  Assuming you are reading  ASCII  Documents 
      ASCIIEncoding Encoding = new ASCIIEncoding();
      int bytesRead;
      do 
      {
        bytesRead = fr.Read(buffer, 0, buffer.Length);
        string content = Encoding.GetString(buffer,0,bytesRead);
        Console.Write("{0}", content);
      }
      while ( bytesRead > 0);
      fr.Close();
      return 0;
    }
    else
    {
      Console.WriteLine("Failed to open requested file");
      return 1;
    }
  }
}

I hope this article is helpful to everyone's C # programming.