title: Apply mask a string in C# asp.net?
body: <p>Hi all in my project i want a currency in three formats,.</p>
  
  <pre><code>1) ...999,999,999
  2) ...999,999,999.00
  3) ...999,999,99
  </code></pre>
  
  <p>The format is specified in mysql data table field. My project is in ASP.NET so I can't use MaskedTextBox . Code I tried:</p>
  
  <pre><code>String.Format("{999,999,999}",rate);
  </code></pre>
  
  <p>and </p>
  
  <pre><code>rate.ToString("999,999,999).
  </code></pre>
  
  <p>How to get the mask string?</p>