How to make a xaml textbox in silverlight accept only numbers with maximum one decimal point precision

Question

How to make a xaml textbox in silverlight accept only numbers with maximum one decimal point precison. I have tried the answers in this question How to make a textBox accept only Numbers and just one decimal point in Windows 8 . But it did not work. How can I do this ?

Answer 1

You can write a function like this,

 txtDiscount.KeyDown += new KeyEventHandler(EnsureNumbers);

//Method to allow only numbers,

void EnsureNumbers(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Tab)
        {
            return; 
        }
        bool result =  EnsureDecimalPlaces();
        if (result == false)
        {
            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);
        }
        else
        {
            e.Handled = true;
        }
    }

Method to ensure only 1 decimal,

  bool EnsureDecimalPlaces()
    {

        string inText = txtDiscount.Text;
        int decPointIndex = inText.IndexOf('.');
        if (decPointIndex < 1 || decPointIndex == 1)
        {
            return false;
        }
        else
            return true;
    }