Array.copy方法

Question

Public Shared Function EncryptRSA(ByVal infilename As String, ByVal outfilename As String, ByVal pubkey As String) As String 
     Dim buffer2 As Byte() 
     Dim buffer3 As Byte() 
     Dim provider As New RSACryptoServiceProvider 
     provider.FromXmlString(File.ReadAllText(pubkey)) 
     Dim sourceArray As Byte() = File.ReadAllBytes(infilename) 
     Dim num As Integer = (sourceArray.Length/&H3A) 
     Dim stream As FileStream = File.Create(outfilename) 
     Dim num2 As Integer = 0 

     For num2 = 0 To num - 1 
      buffer2 = New Byte(&H3A - 1) {} 
      Array.Copy(sourceArray, (num2 * &H3A), buffer2, 0, &H3A) 
      buffer3 = provider.Encrypt(buffer2, True) 
      stream.Write(buffer3, 0, buffer3.Length) 
     Next num2 
     If ((sourceArray.Length Mod &H3A) <> 0) Then 
      buffer2 = New Byte((sourceArray.Length Mod &H3A) - 1) {} 

      Array.Copy(sourceArray, ((sourceArray.Length/&H3A) * &H3A), buffer2, 0, (sourceArray.Length Mod &H3A)) 
      buffer3 = provider.Encrypt(buffer2, True) 
      stream.Write(buffer3, 0, buffer3.Length) 
     End If 
     stream.Close() 
     Return File.ReadAllText(outfilename) 
    End Function 

錯誤1重載決策失敗，因爲沒有可訪問的「複製」可以在不縮小轉換被稱爲： 「公共共享子拷貝（sourceArray作爲System.array，sourceIndex長， destinationArray As System.Array，destinationIndex As Long，Length As Long）'：參數匹配參數'sourceIndex'從'Double'變爲'Long'。 '公共共享子副本'（SourceArray As System.Array，sourceIndex As Integer，destinationArray As System.Array，destinationIndex As Integer，length As Integer）'：參數'sourceIndex'的參數從'Double'變爲'Integer'。 C：\用戶\用戶名\應用程序數據\本地\臨時項目\ WindowsApplication1 \ Crypto.vb 52 13 WindowsApplication1

Answer 1

你有這樣一行：

Array.Copy(sourceArray, ((sourceArray.Length/&H3A) * &H3A), buffer2, 0, (sourceArray.Length Mod &H3A)) 

什麼編譯器要告訴你的是，你提供了一個sourceIndex爲double值，但預期爲長整型值。 double不能長時間隱含，因爲long不能表示double的所有可能值。

所以做明確的轉換：

Array.Copy(sourceArray, CLng((sourceArray.Length/&H3A) * &H3A), buffer2, 0, (sourceArray.Length Mod &H3A))