VB.Net獲取偏移地址

Question

在VB.Net我打開與BinaryReader在文件..

我需要找到一些的十六進制值的文件，如果他們被發現，它返回第一個的偏移地址字節..

這是可能的嗎？怎麼能做到這一點？謝謝

編輯：

我當前的代碼：

Private Function findOffset() 
    Using reader As New BinaryReader(File.Open(filename, FileMode.Open)) 
     ' Loop through length of file. 
     Dim pos As Integer = 0 ' <== THIS IS THE OFFSET 
     Dim length As Integer = reader.BaseStream.Length 
     Do While pos < length 
      ' Read the integer. 
      Dim value As Byte = reader.ReadByte() 
      If value = CByte(&H41) Then 
       Return pos 
       Exit Do 
      End If 
      ' Add length of integer in bytes to position. 
      pos += 1 
     Loop 
    End Using 
End Function 

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
    MsgBox(Hex(findOffset()).ToString.PadLeft(6, "0"c)) 
End Sub 

我想要做的是：

例如，我打開一個文件，在該文件中有開一個十六進制編輯器，我看到有一些十六進制值，41,42,43,44。我需要找到這些值，然後返回找到它們的偏移地址。

與我目前的代碼，它的工作原理，但我只能找到1Byte，我需要找到超過1 .. 我可能需要找到1kb或更多的數據！

我正在找一些bin文件中的可用空間。所以例如我需要10Byte的可用空間。那在Hex heditor中將會是FF,FF,FF,FF,FF,FF,FF,FF,FF,FF，我需要找到它並返回第一個空字節的偏移地址。

編輯2

這裏代碼的第一行。

Private Function findOffset(query as Byte()) 
     Using reader As New BinaryReader(File.Open(filename, FileMode.Open)) 
      Dim startOffset = 80 
      Dim length As Integer = reader.BaseStream.Length - startOffset 
      reader.BaseStream.Position = startOffset 
      If query.Length <= length Then 
      ... 

可是不行的。它告訴我，從十進制自由空間開始偏移00000047

我做錯了什麼在這裏，我不明白你也通過

是什麼意思

修改 「長度」 可變 「長度=長度 - 開始偏移」

Answer 1

Using reader As New BinaryReader(File.Open("file.bin", FileMode.Open)) 
    ' Loop through length of file. 
    Dim pos As Integer = 0 ' <== THIS IS THE OFFSET 
    Dim length As Integer = reader.BaseStream.Length 
    While pos < length 
    ' Read the integer. 
    Dim value As Byte = reader.ReadByte() 
      If value == 123 Then 
       return pos 
      End If 
    ' Write to screen. 
    Console.WriteLine(value) 
    ' Add length of integer in bytes to position. 
    pos += 1 
    End While 
End Using 

略有http://www.dotnetperls.com/binaryreader-vbnet

編輯修改要通過你的函數內部數組搜索你要循環值的數組。

Private Function findOffset(query as Byte()) 
    Using reader As New BinaryReader(File.Open(filename, FileMode.Open)) 
     Dim length As Integer = reader.BaseStream.Length 
     If query.Length <= length Then 
      ' process initial (first) search 
      Dim values As Byte() = reader.ReadBytes(query.Length) 
      Dim found As Boolean = False 
      For fnd = 0 To query.Length - 1 
       If values(fnd) <> query(fnd) Then 
        found = False 
        Exit For 
       End If 
       found = True 
      Next fnd 
      If found = True Then 
       Return 0 
      Else ' keep searching the rest of the binary stream 
       For pos = query.Length To length - 1 
        ' shift values over 1, [1,2,3,4] => [2,3,4,4] 
        Array.Copy(values, 1, values, 0, values.Length - 1) 
        ' put the next new byte at the end 
        values(values.Length - 1) = reader.ReadByte() 
        For fnd = 0 To query.Length - 1 
         If values(fnd) <> query(fnd) Then 
          found = False 
          Exit For 
         End If 
         found = True 
        Next fnd 
        If found = True Then 
         Return pos - (query.Length - 1) 
        End If 
       Next pos 
      End If 
     End If 
    End Using 
    Return -1 ' not found 
End Function 

注意：我沒有測試過上面的代碼，所以可能會出現語法錯誤。