Restricting Key Stokes in text box

Hello

I have an web application (asp.net + C#)

I have an textbox that is always filled with numeric value.

i want to restrict other all the key press except the numeric key & - .
as for the phone the hyphen is required.

How to implement it?

I tried but no success.

Any Idea?

As pressing a key in a web-browser is a client side event, so you will have to use Client Side Javascript to do that.

Here is a script that will allow only numbers in a textbox

Code:

---

        <SCRIPT language=javascript>     
      function isNumberKey(evt)
      {
        var charCode = (evt.which) ? evt.which : event.keyCode
        if (charCode > 45 && (charCode < 48 || charCode > 57))
            return false;
        return true;
      }     
  </SCRIPT>

---

Remember in your HTML part of the TextBox you will have to write this onkeypress="return isNumberKey(event)"