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

Could also simply implement a validation rule and apply it to the TextBox:

With the implementation of the rule as follow (using the same Regex as proposed in other answers):

public class OnlyDigitsValidationRule : ValidationRule
{
    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        var validationResult = new ValidationResult(true, null);

        if(value != null)
        {
            if (!string.IsNullOrEmpty(value.ToString()))
            {
                var regex = new Regex("[^0-9.-]+"); //regex that matches disallowed text
                var parsingOk = !regex.IsMatch(value.ToString());
                if (!parsingOk)
                {
                    validationResult = new ValidationResult(false, "Illegal Characters, Please Enter Numeric Value");
                }
            }
        }

        return validationResult;
    }
}