title: TextBox money format with 1 comma
body: <p>I have a textbox in c# winforms.</p>
  
  <pre><code>   private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
      {
          if (!char.IsNumber(e.KeyChar) &amp; (Keys)e.KeyChar != Keys.Back
                  &amp; e.KeyChar != ',')
          {
              e.Handled = true;
          }
  
          base.OnKeyPress(e);
      }
  </code></pre>
  
  <p>above code works very well however i can add 2 comma like <strong>"100,,00"</strong>.How can i only let user add <strong>"100,00"</strong> or <strong>"100,000,000"</strong> with 1 comma as money format ?</p>
  
  <p>Any help will be appreciated.</p>
  
  <p>Thanks.</p>