How do I get a TextBox to only accept numeric input in WPF?

Question

I\'m looking to accept digits and the decimal point, but no sign.

I\'ve looked at samples using the NumericUpDown control for Windows Forms, and this sample of a Num

Answer 1

For those looking for a quick and very simple implementation for this type of problem using only integers and decimal, in your XAML file, add a PreviewTextInput property to your TextBoxand then in your xaml.cs file use:

private void Text_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
    e.Handled = !char.IsDigit(e.Text.Last()) && !e.Text.Last() == '.';
}

It's kind of redundant to keep checking the entire string every time unless, as others have mentioned, you're doing something with scientific notation (albeit, if you're adding certain characters like 'e', a simple regex adding symbols/characters is really simple and illustrated in other answers). But for simple floating point values, this solution will suffice.

Written as a one-liner with a lambda expression:

private void Text_PreviewTextInput(object sender, TextCompositionEventArgs e) => e.Handled = !char.IsDigit(e.Text.Last() && !e.Text.Last() == '.');