VBA自定义函数：可将特别大的十进制数转换成二进制数

Function LongDec2Bin(ByVal nIn As Long, _
         Optional nBits As Long = 0&) As Variant
 Dim nReqBits As Long
 Dim sOut As String
 Dim sBit As String
 Dim bNeg As Boolean
 Dim i As Long
 If nIn < 0& Then
   bNeg = True
   nIn = -(nIn + 1&)
 End If
 If nIn = 0& Then
   nReqBits = 1&
 Else
   nReqBits = Int(Log(nIn) / Log(2&)) + 1& - bNeg
 End If
 If nBits <= 0& Then nBits = nReqBits
 If nBits >= nReqBits Then
   If bNeg Then
     sOut = String(nBits, "1")
     sBit = "0"
   Else
     sOut = String(nBits, "0")
     sBit = "1"
   End If
   For i = nBits To (nBits - nReqBits + 1&) Step -1
     If (nIn - 2& * (nIn \ 2&)) > 0 _
         Then Mid(sOut, i, 1&) = sBit
     nIn = nIn \ 2&
   Next i
   LongDec2Bin = sOut
 Else
   LongDec2Bin = CVErr(xlErrNum)
 End If
End Function