[RESOLVED] FileStream, ReadBytes with interval

[rossi_4656]

I'm trying to read bytes with 1200 interval for 100 times, but I can't get it working. This is my code:

Try
                Dim fr As FileStream = File.OpenRead(OpenFileDialog1.FileName)
                Dim data(fr.Length) As Byte
                Using reader As New BinaryReader(fr)
                    Const START As Long = 4896
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                End Using
                ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
                fr.Close()
            Catch
            End Try

I need to read from offset 4896, then from 6096, then from 7296 for 100 times and for each interval add to the listbox. who can help me? Thanks

[Niya]

I dont get it.....is that code executed by a timer ? What exactly is it doing that its not supposed to ?
Need more information.

[rossi_4656]

No this code is executed by a button, and I need to read data from offset 4896, then 6096, then 7296... for 100 times. The interval is offset 1200.

Example for read data to offset 4896 and then to 6096 and add those 2 items to listbox:

Button1.Click........

Try
                Dim fr As FileStream = File.OpenRead(OpenFileDialog1.FileName)
                Dim data(fr.Length) As Byte
                Using reader As New BinaryReader(fr)
                    Const START As Long = 4896
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                End Using
                ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
                fr.Close()
            Catch
            End TryTry
                Dim fr As FileStream = File.OpenRead(OpenFileDialog1.FileName)
                Dim data(fr.Length) As Byte
                Using reader As New BinaryReader(fr)
                    Const START As Long = 6096
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                End Using
                ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
                fr.Close()
            Catch
            End Try

Regular offset interval = 1200

But it's hard to do if I want to read 100 datas so I'm looking for a fast way

[opus]

Did soem changes to make a 100* Times Loop to step through the Stream. No checking for EndOfStream
Is that assingment to a new ListBox1.Item correct? (Only the last value of Data, not the previous ones?)

Try
            Dim fr As FileStream = File.OpenRead("test.txt")
            Dim data(fr.Length) As Byte
            Using reader As New BinaryReader(fr)
                Dim START As Long = 4896
                Dim i As Integer = 0
                Do
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                    START += 1200
                    i += 1
                Loop Until i = 100 ' do loop is done 100 times!
                fr.Seek(START, SeekOrigin.Begin)
                data = reader.ReadBytes(data.Length)
            End Using
            ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
            fr.Close()
        Catch
        End Try

[rossi_4656]

Did soem changes to make a 100* Times Loop to step through the Stream. No checking for EndOfStream
Is that assingment to a new ListBox1.Item correct? (Only the last value of Data, not the previous ones?)

Try
            Dim fr As FileStream = File.OpenRead("test.txt")
            Dim data(fr.Length) As Byte
            Using reader As New BinaryReader(fr)
                Dim START As Long = 4896
                Dim i As Integer = 0
                Do
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                    START += 1200
                    i += 1
                Loop Until i = 100 ' do loop is done 100 times!
                fr.Seek(START, SeekOrigin.Begin)
                data = reader.ReadBytes(data.Length)
            End Using
            ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
            fr.Close()
        Catch
        End Try

Thanks for the code, but I need to read also previews data. Anyway I've made some changes and I've resolved, thank you very much!

This is the working code:

Try
            Dim fr As FileStream = File.OpenRead(OpenFileDialog1.FileName)
            Dim data(fr.Length) As Byte
            Using reader As New BinaryReader(fr)
                Dim START As Long = 4896
                Dim i As Integer = 0
                Do
                    START += 1200
                    i += 1
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                    ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
                Loop Until i = 100 ' do loop is done 100 times!
            End Using
            fr.Close()
        Catch
        End Try

[opus]

Thanks for the code, but I need to read also previews data. Anyway I've made some changes and I've resolved, thank you very much!

This is the working code:

Try
            Dim fr As FileStream = File.OpenRead(OpenFileDialog1.FileName)
            Dim data(fr.Length) As Byte
            Using reader As New BinaryReader(fr)
                Dim START As Long = 4896
                Dim i As Integer = 0
                Do
                    START += 1200
                    i += 1
                    fr.Seek(START, SeekOrigin.Begin)
                    data = reader.ReadBytes(data.Length)
                    ListBox1.Items.Add(System.Text.Encoding.UTF8.GetString(data))
                Loop Until i = 100 ' do loop is done 100 times!
            End Using
            fr.Close()
        Catch
        End Try

In my humble opinion you are not reading any PREVIOUS data with your code, you start to read from byte# 6096!

[rossi_4656]

In my humble opinion you are not reading any PREVIOUS data with your code, you start to read from byte# 6096!

Well, I've tryed the code and it's working . Anyway my datas are hex values, maybe this is the reason that the code it's working

Example data at offset 6096:

56 41 4C 55 45 20 31 00 00

So the program read from offset 6096 to 7002, then loop to offset 7296 (+1200)