Trying to figure out memorystreams and byte arrays

[cpopham]

Okay,

 

I am attempting to learn more about memorystreams and byte arrays as well because I think my hashing and crytography problems are arising from this area. I am reading a text file into an array, extracting a portion of the array to a memorystream, then writing that back out to disk. Just to see what is going on. Okay, I have everything working fine except the extracting of a portion of the array to the memorystream.

 

Since it is string characters, I am doing something simple, I only want the last 9 characters of the original text file.

I thought that I could use length - 9 to get those, or maybe since it is 0 based length - 10. However, that is not the case, to get the last 9 characters, I have to say something like length-11. Why 11? This is an odd number to me. Am I missing something here?

 

Here is my code:

       Dim encoder As New UTF8Encoding '/Create UTF8 encoding (has more applications than ASCII)
       Dim fsIn As New FileStream(strOutFileArray, FileMode.Open, FileAccess.Read, FileShare.ReadWrite) '/Setup input filestream
       Dim rdIn As New StreamReader(fsIn) '/Setup streamreader
       Dim myfile As Byte() '/ByteArray to hold input file
       myfile = encoder.GetBytes(rdIn.ReadToEnd) '/Read input file in
       Dim msstream As New MemoryStream(11) '/Setup memorystream to hold data with length of data
       msstream.Write(myfile, myfile.Length - 11, 11) '/Convert byte array of data to memorystream
       Dim after As Byte() '/Byte array to hole data from memorystream
       after = msstream.ToArray '/Convert memorystream to byte array

       'Dim intLength As Integer = msstream.Length / 8
       'Dim strLength As String = intLength
       'strLength = strLength.PadLeft(9, "0")
       'Dim strJunk As String = "WE DO NOT WANT THIS LINE"

       '/Setup output Filestream
       Dim fsOut As New FileStream(strOutFileArray2, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite)
       Dim wr As New StreamWriter(fsOut) '/Setup streamwriter to output data
       wr.Write(encoder.GetString(after)) '/Convert byte array to string and write it to disk
       'wr.WriteLine(strJunk)
       'wr.WriteLine(strLength)
       wr.Flush() '/Flush the streamwriter to make sure all data is written to disk

Could someone please explain this to me?

 

Thanks, Chester

Edited January 12, 2006 by PlausiblyDamp