Formatting a Textbox (Phone Numbers, Mobile Numbers, Emails)
<p>I'd like to know how to cast textbox input into different formats. I tried using Format.String() since it's the 'solution' I found online after doing some research but it did not end well for me. </p>

<pre><code>  private void RegHomePhoneTBox_TextChanged(object sender, EventArgs e)
    {
        string s = RegHomePhoneTBox.Text;
        double sAsD = double.Parse(s);
        RegHomePhoneTBox.Text = string.Format("{0:###-####}", sAsD).ToString();
    }
</code></pre>

<p>This was the code block I used and it just keep on throwing an error.</p>

<blockquote>
  <p>An unhandled exception of type 'System.FormatException' occurred in
  mscorlib.dll Additional information: Input string was not in a correct
  format.</p>
</blockquote>