如何驗證第一名是僅在vb中使用小數？

Question

我想驗證一個文本框，如果它只在第一位取小數。沒有0或任何數字（例如：.5不是0.5）請幫助我。在此先感謝

Answer 1

我就把文本框名爲TextBox1的和一個名爲Button1的按鈕，寫了下面的代碼上的Button1 Click事件：

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
     Dim getstr As String = TextBox1.Text.Substring(0, 1) 
     If getstr = "." Then 
      MsgBox("Your input's first place is a '.' - validated.") 
     End If 
    End Sub 

Answer 2

如何像這樣的功能...

Private Function do_validate(ByRef curr_textbox As TextBox) As Boolean 
    Dim to_return As Boolean = False 

    Try 
     Dim curr_input_text As String = curr_textbox.Text 

     If (Len(curr_input_text > 0)) Then 
      Dim left_most As String = Mid(curr_input_text, 1, 1) 
      If left_most = "." Then 
       to_return = True 
      End If 
     End If 

    Catch 
    Finally 
     Select Case to_return 
      Case True 
       curr_textbox.BackColor = Color.LightGreen 
      Case False 
       curr_textbox.BackColor = Color.LightPink 
     End Select 
    End Try 

    Return to_return 
End Function 

然後它可以像這個do_validate（txt_input）一樣從TextBox.TextChanged事件中調用。它也可以作爲驗證序列的一部分從提交按鈕中調用。