base64编码解码函数

最新推荐文章于 2025-06-19 17:49:09 发布

原创最新推荐文章于 2025-06-19 17:49:09 发布 · 672 阅读

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<%
Function bin2dec(binStr)
towPow = 1
numLen = len(binStr)
bin2Dec = 0
decPos = numLen
Do While decPos>0
  cChar = mid(binStr,decPos,1)
  nChar = Cint(cChar)
  bin2Dec = bin2Dec+nChar*towPow
  towPow = towPow*2
  decPos = decPos-1
Loop
End Function

Function dec2bin(octNumber)
vara = octNumber
Do
dec2bin = cstr(vara mod 2) & dec2bin
vara = vara / 2
loop until vara = 0
End Function

Bstr_base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/ = "

Function enCode_base64(strBin)
bins = ""
for i = 1 to lenB(strBin)
  varTm = AscB(midB(strBin,i,1))
  bins = bins & right("00000000" & dec2bin(varTm),8)
  If i mod 3 = 0 Then
   for w = 0 to 3
    sixBin = mid(bins,w*6+1,6)
    nChar = bin2Dec(sixBin)+1
    enCode_base64 = enCode_base64 & mid(Bstr_base64,nChar,1)
   next
   bins = ""
  End If
next

If bins <> "" Then
  pads = 3-len(bins) / 8
  exitLoop = False
  Do While Not exitLoop
   nChar = left(bins,6)
   If len(nChar)<6 Then
    nChar = left(nChar & "000000",6)
    exitLoop = True
   End If
   nNum = bin2dec(nChar)+1
   enCode_base64 = enCode_base64 & mid(Bstr_base64,nNum,1)
   bins = mid(bins,7)
  Loop
  enCode_base64 = enCode_base64 & String(pads," = ")
End If
End Function

Function deCode_base64(baseStr)
If len(baseStr) mod 4 <> 0 Then
  exit Function
End If
bins = ""
for i = 1 to Len(baseStr)
  nChar = mid(baseStr,i,1)
  If nChar = " = " Then
   exit for
  End If
  oldValue = inStr(Bstr_base64,nChar)-1
  binValue = right("000000" & dec2bin(oldValue),6)
  bins = bins & binValue

  If len(bins) >= 8 Then
   deChar = left(bins,8)
   bins = mid(bins,9)
   deCode_base64 = deCode_base64 & chrB(bin2Dec(deChar))
  End If
next
End Function
%>