Regular Expressions for validation control

I found a good website for getting and learning regular expressions for our validation needs. http://www.regular-expressions.info/

Creating Regular Expression for Numeric Values and using it on a TextBox control in C#

//Creating regular expression for numeric values
Regex rxNum = new Regex(@"^[0-9\s]+$");

//using regular expression on  a TextBox Control in C#
if (!rxNum.IsMatch(textbox1.Text))
          Response.write("Textbox1 has Numeric value");