FileDiff2 Optimized

• Download source code - 48.4 KB

Introduction

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;

do
{
    // 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
        //
        do
        {
            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);

streamA.Close();
streamB.Close();

History

• 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.