Validating a numeric only textbox
<p>I've created a form based program that need some validation, all I need to to make sure the user can only enter numeric value in the distance text field</p>

<p>So far, I've checked that it's got something in it, if it has something then go on to validate it's numeric</p>

<pre><code>else if (txtEvDistance.Text.Length == 0)
        {
            MessageBox.Show("Please enter the distance");
        }
else if (cboAddEvent.Text //is numeric)
        {
            MessageBox.Show("Please enter a valid numeric distance");
        }
</code></pre>
