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