Question

我有一个带有文本框的Silverlight应用程序，其输入我只想限制为十进制数。在网上搜索我遇到了以下可能的解决方案（好奇地在不同的地方，不同的人声称同一行代码的作者）它似乎运作良好，除了在输入至少1个数字后，它将允许输入大写或小写字母'd'，我无法弄清楚为什么会这样，因此无法弄清楚如何防止这种情况发生。有谁能请提供解决方案。非常感谢。

    private void Unit_KeyDown(object sender, KeyEventArgs e)
    {

        if (e.Key == Key.Tab)
        {

        }
        var thisKeyStr = "";
        if (e.PlatformKeyCode == 190 || e.PlatformKeyCode == 110)
        {
            thisKeyStr = ".";
        }
        else
        {
            thisKeyStr = e.Key.ToString().Replace("D", "").Replace("NumPad", "");
        }
        var s = (sender as TextBox).Text + thisKeyStr;
        var rStr = "^[0-9]+[.]?[0-9]*$";
        var r = new Regex(rStr, RegexOptions.IgnoreCase);
        e.Handled = !r.IsMatch(s);

    }

Answer 1

您可以尝试以下方法：

将else替换为else if (e.Key != Key.D)或

设置Handled属性，如下所示：

e.Handled = !r.IsMatch(s) || string.IsNullOrEmpty(thisKeyStr);

// also possible:
e.Handled = !r.IsMatch(s) || e.Key == Key.D;

Answer 2

这是一个更简单的代码优化。没有对象创建;没有字符串比较和NO正则表达式验证

private static void TextBox_KeyDown(object sender, KeyEventArgs e)
    {
        //platform code for Hyphen which is not same as Subtract symbol but in our case both give same meaning
        const int KEYCODE_Hyphen_OnKeyboard = 189;
        const int KEYCODE_Dot_OnKeyboard = 190;
        const int KEYCODE_Dot_OnNumericKeyPad = 110;

        e.Handled = !(
            (!( //No modifier key must be pressed
                 (Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift
              || (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control
              || (Keyboard.Modifiers & ModifierKeys.Alt) == ModifierKeys.Alt
            )
          && ( //only these keys are supported
                (e.Key >= Key.D0 && e.Key <= Key.D9) || (e.Key >= Key.NumPad0 && e.Key <= Key.NumPad9)
              || e.Key == Key.Subtract || e.Key == Key.Add || e.Key == Key.Decimal
              || e.Key == Key.Home || e.Key == Key.End || e.Key == Key.Delete
              || e.Key == Key.Tab || e.Key == Key.Enter || e.Key == Key.Escape || e.Key == Key.Back
              || (e.Key == Key.Unknown && (
                         e.PlatformKeyCode == KEYCODE_Hyphen_OnKeyboard
                      || e.PlatformKeyCode == KEYCODE_Dot_OnKeyboard || e.PlatformKeyCode == KEYCODE_Dot_OnNumericKeyPad
                    )
                 )
             )
          )
        );
    }

Answer 3

      private void TextBox_KeyDown(object sender, KeyEventArgs e)
    {
        bool isDigit = e.Key >= Key.D0 && e.Key < Key.D9 || e.Key == Key.NumPad0 || e.Key == Key.NumPad1 || e.Key == Key.NumPad2 || e.Key == Key.NumPad3 || e.Key == Key.NumPad4 || e.Key == Key.NumPad5 || e.Key == Key.NumPad6 ||
        e.Key == Key.NumPad7 || e.Key == Key.NumPad8 || e.Key == Key.NumPad9 ||e.Key == Key.Back || e.Key == Key.Delete || e.Key == Key.Left || e.Key == Key.Right;

        if (isDigit) { }
        else
            e.Handled = true; 
    }

Silverlight文本框只接受小数

3 个答案: