Remove html tags from string in Asp.net

  public static string StripHtml(string html, bool allowHarmlessTags)

    {

        if (html == null || html == string.Empty)

            return string.Empty;

        if (allowHarmlessTags)

        {

            return System.Text.RegularExpressions.Regex.Replace(html, "", string.Empty);

        }

        return System.Text.RegularExpressions.Regex.Replace(html, "<[^>]*>", string.Empty);

    }

Email Validation in ASP.net

protected  bool EvaluateIsValid()

    {

        string val = txtEmail.Text;

        string pattern = @"^[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)?@[a-z][a-z|0-9|]*\.([a-z][a-z|0-9]*(\.[a-z][a-z|0-9]*)?)$";

        Match match = Regex.Match(val.Trim(), pattern, RegexOptions.IgnoreCase);

        if (match.Success)

            return true;

        else

            return false;

    }

Disable copy paste in asp.net textbox

<asp:TextBox ID="TextBox1" runat="server"

oncopy="return false"

onpaste="return false"

oncut="return false">

</asp:TextBox>

Disable Right Click -Asp.Net

<script language="JavaScript">

      // on right click appear this message

      var DisplayMsg="Right Click Disabled";

      //return message

      function clickBYIE()

      {

          if(document.all)

          {

              alert(DisplayMsg);

              return false;

          }

      }

      //return message

      function clickBYNS(e)

      {

          if (document.layers||(document.getElementById&&!document.all))

          {

              if (e.which==2||e.which==3)

              {

               alert(DisplayMsg);

               return false;

              }

          }

      }

     //set the function as per browser

      if (document.layers)

      {

          document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickBYNS;

      }

      else

      {

          document.onmouseup=clickBYNS;document.oncontextmenu=clickBYIE;

      }

      //disabled the right click on the browser

       document.oncontextmenu=new Function("return false")

  </script>

Set Default Button in ASP.NET

<form id="form1" runat="server" defaultbutton="Button1">

   <asp:TextBox ID="Textbox1" runat="server" />

   <asp:TextBox ID="Textbox2" runat="server" />

   <asp:Button ID="Button1" runat="server" Text="Submit" />

   <asp:Button ID="Button2" runat="server" Text="Cancel" />

</form>