title: Why TextBox validation doesn't work
body: <p>I wish to validate this <code>TextBox</code> against negative values and characters (must be integer without decimal)
  It works well for <code>.</code> but I am not able to understand why it accepts negative value and characters?</p>
  
  <p>My code is :</p>
  
  <pre><code>private void txtLifeMonths_KeyPress(object sender, KeyPressEventArgs e)
  {
      if (!Char.IsDigit(e.KeyChar) &amp;&amp; (e.KeyChar == '.') &amp;&amp; (e.KeyChar &gt;= 0) &amp;&amp; (e.KeyChar != (char)Keys.Back))
          e.Handled = true;
  }
  </code></pre>