Random access file IO - what is wrong with this code?

[Phil]

Problem code:

using System;
using System.Collecti ons.Generic;
using System.Text;
using System.IO;
using System.Diagnost ics;

namespace Streams {
class Program {
static void Main(string[] args) {
const string file = @"C:\Temp\file. txt";

if (File.Exists(fi le))
File.Delete(fil e);

using (StreamWriter sw = new StreamWriter(fi le)) {
sw.WriteLine("L ine 1");
sw.WriteLine("L ine 2");
sw.WriteLine("L ine 3");

FileStream fs = sw.BaseStream as FileStream;
Debug.Assert(fs != null);

fs.Seek(0, SeekOrigin.Begi n);
sw.WriteLine("L ine A");
}
}
}
}

Expected result: a file with 3 lines
Line A
Line 2
Line 3

Actual result: a file with 4 lines
Line 1
Line 2
Line 3
Line A


The Seek() is being ignored.

Obviously I am doing something wrong - any hints guys?!


--
Phil

[Michael]

Re: Random access file IO - what is wrong with this code?

Hi,

..Flush() makes it work:

sw.WriteLine("L ine 1");
sw.WriteLine("L ine 2");
sw.WriteLine("L ine 3");
sw.Flush();
FileStream fs = sw.BaseStream as FileStream;
Debug.Assert(fs != null);
fs.Seek(0, SeekOrigin.Begi n);
sw.WriteLine("L ine A");
sw.Flush();

not sure it's the best solution...

Mike

http://www.seeknsnatch.com

"Phil" <foo@foo.comwro te in message
news:a137e2l75i fs3s29b4tj0to9o afskjsbtv@4ax.c om...

Problem code:
>
using System;
using System.Collecti ons.Generic;
using System.Text;
using System.IO;
using System.Diagnost ics;
>
namespace Streams {
class Program {
static void Main(string[] args) {
const string file = @"C:\Temp\file. txt";
>
if (File.Exists(fi le))
File.Delete(fil e);
>
using (StreamWriter sw = new StreamWriter(fi le)) {
sw.WriteLine("L ine 1");
sw.WriteLine("L ine 2");
sw.WriteLine("L ine 3");
>
FileStream fs = sw.BaseStream as FileStream;
Debug.Assert(fs != null);
>
fs.Seek(0, SeekOrigin.Begi n);
sw.WriteLine("L ine A");
}
}
}
}
>
Expected result: a file with 3 lines
Line A
Line 2
Line 3
>
Actual result: a file with 4 lines
Line 1
Line 2
Line 3
Line A
>
>
The Seek() is being ignored.
>
Obviously I am doing something wrong - any hints guys?!
>
>
--
Phil

[Phil]

Re: Random access file IO - what is wrong with this code?

On Thu, 17 Aug 2006 00:10:15 +0200, "Michael" <info@seeknsnat ch.com>
wrote:

>Hi,
>
>.Flush() makes it work:
>
>sw.WriteLine(" Line 1");
>sw.WriteLine(" Line 2");
>sw.WriteLine(" Line 3");
>sw.Flush();
>FileStream fs = sw.BaseStream as FileStream;
>Debug.Assert(f s != null);
>fs.Seek(0, SeekOrigin.Begi n);
>sw.WriteLine(" Line A");
>sw.Flush();
>
>not sure it's the best solution...
>
>Mike
>http://www.seeknsnatch.com

Thanks Michael I will give that a shot.
--
Phil