CH3CH2COOH 如何转化为CH3CH2CH2CH2COOOH?

我不知道你到底是什么意思?
是与VB编程有关的吗/.?
如果是替换的功能的话.下面代码也许能帮你

'如何替换字符串

'需要控件:command1
Public Function sReplace(String1 As String, String2 As String, RepString As String) As String
Dim I As Integer
I = 1
Do
If (I > Len(String1)) Then Exit Do
I = InStr(I, String1, String2)
If I Then
String1 = Left$(String1, I - 1) + RepString + Mid$(String1, I + Len(String2))
I = I + 1
DoEvents
End If
Loop While I
sReplace = String1
End Function

Private Sub Command1_Click()
Dim StrData As String
StrData = "CH3CH2COOH,CH3CH2CH2CH2COOOH"
MsgBox sReplace(StrData, "CH3CH2COOH", "CH3CH2CH2CH2COOOH")
End Sub

'如果不是VB编程的话,偶帮不上你了.不好意思