限制文本框的输入（只输入数字）
文本框防止非法字符输入：
只输入整数：
Private Sub Text1_KeyPress(KeyAscii As Integer)
Select Case KeyAscii
Case Asc("0") To Asc("9"), vbKeyBack
'nop
Case Else
KeyAscii = 0
End Select
End Sub
只输入小数:
Private Sub Text1_KeyPress(KeyAscii As Integer)
Select Case KeyAscii
Case Asc("0") To Asc("9"), vbKeyBack
'nop
case Asc(".")'允许一个小数点
If InStr(1, Text1.Text, ".") > 0 Then KeyAscii = 0
Case Else
KeyAscii = 0
End Select
End Sub