vb 同时改变输入字母大小写 现在只能改变最初输入的大写或小写 为什么

你是要把输的小写变成大写，大写字母变成小写是吧？你写的代码有地方不对，如下修改就行，不懂再问吧

Private Sub Form_Load()

Text1 = ""

Text2 = ""

End Sub

Private Sub Text1_Change()

Dim i As Integer, b As Integer, c As String

For i = 1 To Len(Text1)

  b = Asc(Mid(Text1, i))

  If b >= 65 And b <= 90 Then

      c = c + LCase(Chr(b))

  ElseIf b >= 97 And b <= 122 Then

      c = c + UCase(Chr(b))

  Else

      c = c + Chr(b)

  End If

Next

Text2 = c

End Sub