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FileDiff2 Optimized

, 13 Aug 2009
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A file diff utility.


This application is pretty basic, it uses FileStream objects to perform its task.

Using the code

ASCIIEncoding Encode = new ASCIIEncoding();

// Open the files
FileStream streamA = File.OpenRead(args[0]);
FileStream streamB = File.OpenRead(args[1]);

// Get the stream length
// (so we don't have to caluculate this a million times)
long lenA = streamA.Length - 1;
long lenB = streamB.Length - 1;

// Read the bytes
int byteA;
int byteB;

    // Read the streams
    byteA = streamA.ReadByte();
    byteB = streamB.ReadByte();

    // Are they the same
    if (byteA != byteB)
        // Remember where we parked the car
        long startPos = streamB.Position;

        // Read streamB until we = StreamA
            byteB = streamB.ReadByte();
        while (byteA != byteB && streamB.Position <= lenB);

        // How long is the difference?
        long length = streamB.Position - startPos;

        // Read the bytes
        byte[] theseBytes = new byte[length];
        streamB.Seek(length * -1, SeekOrigin.Current);|
        streamB.Read(theseBytes, 0, (int)length);

        Console.WriteLine("Pos:{0}, Len:{1}, Str:{2}", startPos, 
                          length, Encode.GetString(theseBytes));
while (streamA.Position <= lenA && streamB.Position <= lenB);



  • Aug 12, 2009: Written.
  • Aug 13, 2009: Rewritten to be more explicit, and I modified the file seeking and some variables to bring this down form 57ms run time to 27ms run time.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Matthew Hazlett
Web Developer
United States United States
I started programming for fun when I was about 10 on an Franklin Ace 1000.
I still do it just for fun but it has gotten me a few jobs over the years. More then I can say for my Microsoft Certifications. Smile | :)
The way I learned was by example, now its time to give back to the next generation of coders.

Comments and Discussions

GeneralWorks, but that's it... PinmemberRasqual Twilight22-Aug-09 0:58 
GeneralMy solution Pinmemberpsouza4micronet14-Aug-09 6:31 
GeneralRe: My solution PinmemberMatthew Hazlett14-Aug-09 8:51 
GeneralRe: My solution Pinmemberpsouza4micronet20-Aug-09 10:33 
GeneralRe: My solution PinmemberMatthew Hazlett21-Aug-09 20:07 
GeneralRe: My solution PinmemberPeter Souza25-Aug-09 6:56 
GeneralRe: My solution PinmemberMatthew Hazlett25-Aug-09 8:09 
GeneralRe: My solution PinmemberPeter Souza25-Aug-09 8:15 
GeneralRe: My solution PinmemberMatthew Hazlett25-Aug-09 19:38 
GeneralSome thoughts... Pinmemberpsouza4micronet13-Aug-09 13:50 
GeneralRe: Some thoughts... PinmemberMatthew Hazlett13-Aug-09 14:52 
GeneralRe: Some thoughts... Pinmemberpsouza4micronet13-Aug-09 16:07 
GeneralRe: Some thoughts... PinmemberMatthew Hazlett13-Aug-09 16:41 
GeneralRe: Some thoughts... Pinmemberpsouza4micronet14-Aug-09 1:59 

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