Question

I read a binary file of 900 bytes with much informations inside.
Like this:

     Dim myFile As String = txt_mydir.Text + "\MY_FILE.BIN"
     If IO.File.Exists(myFile) Then
        Dim fInfo As New FileInfo(myFile)
        Dim numBytes As Long = fInfo.Length
        Dim fStream As New FileStream(myFile, FileMode.Open, FileAccess.Read)
        Dim br As New BinaryReader(fStream)
        Dim data As Byte() = br.ReadBytes(CInt(numBytes))

All bytes finishes in bytearray ‘data’.

Now I have to read a numbers written with VB6 structs into that file. Structs are mine and I know what is what and where is what.
For example I need a VB.NET ‘short’ number which is at bytes 81 and 82.
Among that I have all other basic number types to get out.

How to take out desired number of bytes from ‘data’ from specific location, with exact length and get a proper number from it (short, int, double…)?

Answer 1

Use the methods of the BinaryReader to get the fields of your original struct

Dim i As Integer = br.ReadInt32()
Dim d As Double = br.ReadDouble()
Dim s As String = br.ReadString()

And so on. You must read the fields in exactly the same order as they were written to the file.

Embed it into a loop like this

While br.BaseStream.Position() <> inFile.BaseStream.Length()
    ...
End While