例如一个字符串“1,2,3,4,5,6,7,8,9,0,11,12,13,14,15,16,17,18,19,20,1,2,3,4,5,6,7,8,9,0,11,12,13,14,15,16,17,18,19,20,1,2,3,4,5,6,7,8,9,0,11,12,13,14,15,16,17,18,19,20,”，我想Split后将第5个和第15个替换成0后生成新的字符串，我写的程序如下：

Dim a As String
Dim b() As String
Dim temp1 As String
Dim temp2 As String
Dim i As Integer
Dim c As String


Private Sub Command1_Click()
temp1 = ""
b = Split(a, ",")
b(5) = 0
b(15) = 0
For i = 0 To UBound(b) - 1
temp1 = temp1 & b(i) & ","
Next i
Text1.Text = temp1
End Sub

Private Sub Command2_Click()
temp2 = ""
b = Split(a, ",")
c = 0
temp2 = Replace(a, b(5), c)
Text2.Text = temp2
End Sub

Private Sub Form_Load()
Text1.Text = ""
Text2.Text = ""
a = "1,2,3,4,5,6,7,8,9,0,11,12,13,14,15,16,17,18,19,20,1,2,3,4,5,6,7,8,9,0,11,12,13,14,15,16,17,18,19,20,1,2,3,4,5,6,7,8,9,0,11,12,13,14,15,16,17,18,19,20,"
End Sub

Command1用循环方式生成新的字符串（结果正确），Command2用Replace替换（结果不对）。

想请教一下，生成新的字符串一定要用Command1方式循环得出吗？我的每个文件中类似的字符串有数万行，每行的UBound(b)没有规律且不一致，同时想处理数十到数百个文件，每行都做个循环生成新字符串然后重新写成新文件，似乎效率太低，有什么好办法吗？