Numeric Data Entry in WPF

Question

How are you handling the entry of numeric values in WPF applications?

Without a NumericUpDown control, I\'ve been using a TextBox and handling its PreviewKeyDown eve

Answer 1

This is how I do it. It uses a regular expression to check if the text that will be in the box is numeric or not.

Regex NumEx = new Regex(@"^-?\d*\.?\d*$");

private void TextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
    if (sender is TextBox)
    {
        string text = (sender as TextBox).Text + e.Text;
        e.Handled = !NumEx.IsMatch(text);
    }
    else
        throw new NotImplementedException("TextBox_PreviewTextInput Can only Handle TextBoxes");
}

There is now a much better way to do this in WPF and Silverlight. If your control is bound to a property, all you have to do is change your binding statement a bit. Use the following for your binding:

Note that you can use this on custom properties too, all you have to do is throw an exception if the value in the box is invalid and the control will get highlighted with a red border. If you click on the upper right of the red border then the exception message will pop up.