如何以更好的方式使用KeyDown事件验证？

Question

I have several TextBoxes which need to allow only numeric inputs. The problem is I have to copy & paste the code below for another TextBox that allows only numeric values. Is there any simpler way to implement? such as using functions or inheritance?

private void txtCheckVoucher_Amount_KeyDown(object sender, KeyEventArgs e)
{
     if (Control.ModifierKeys == Keys.Shift)
     {
           e.SuppressKeyPress = true;
           return;
     }

     if (((e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9) ||
             (e.KeyCode >= Keys.NumPad0 && e.KeyCode <= Keys.NumPad9) ||
              e.KeyCode == Keys.Decimal || e.KeyCode == Keys.OemPeriod ||
              e.KeyCode == Keys.Back || e.KeyCode == Keys.Tab ||
              e.KeyCode == Keys.Left || e.KeyCode == Keys.Right ||
              e.KeyCode == Keys.End || e.KeyCode == Keys.Home ||
              e.KeyCode == Keys.ShiftKey || e.KeyCode == Keys.Delete))
     {

     }
     else if (e.KeyCode >= Keys.A || e.KeyCode <= Keys.Z)
              e.SuppressKeyPress = true;
}

Answer 1

You can do this in three way

1. You can have common function which will check the entered key is valid or not. And you call that function from all key down event handlers. This is suitable if you have textbox on different forms.
2. If all the text boxes are on same form, in that case, bind all key down event handler to same function.
3. You can have your custom textbox control which will accept only required keys. Check this post, it might help you.

In general, you can retrieve the textbox control id/name by ((System.Windows.Forms.Control)(sender)).Name

Hope this helps.

Answer 2

If the textboxes need the same KeyDown event logic, why not just subscribe both textboxes to the same event handler?

You can just set the KeyDown event to the same txtCheckVoucher_Amount_KeyDown() method.

Answer 3

您可以从所有其他文本框的KeyDown事件中调用txtCheckVoucher_Amount_KeyDown（）。

Answer 4

简单地将相同的KeyDown事件txtCheckVoucher_Amount_KeyDown()分配给所有文本框