Checking if a string is numeric in C#

 int sidNumber;
 bool isInteger = Int32.TryParse(sid, out sidNumber);

Add a JavaScript alert box

http://www.beansoftware.com/ASP.NET-Tutorials/Message-Box.aspx

http://www.dotnetspider.com/forum/ViewForum.aspx?ForumId=32564

Credits to chakravarthy

string tmp = "";
tmp = "";
Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "MyScript", tmp);
and if u want to alert message for Exceptions 
string tmp = "";
tmp = "";
Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "MyScript", tmp);

Adding Client-Side Confirmation When Deleting

http://www.asp.net/data-access/tutorials/adding-client-side-confirmation-when-deleting-cs

Here's some example code

<asp:LinkButton ID="DeleteButton" runat="server" CausesValidation="True" 
                        CommandName="Delete" Text="Delete" OnClientClick="return confirm('Are you sure you wish to delete this record?');" />                

 

Export DataGrid to Excel, MS Word and Textfile

At first, I used this one first
http://www.codersource.net/asp-net/asp-net-miscellaneous/exporting-data-grid-to-excel-using-c.aspx

Then I found another one. This one works well for me :)
http://archive.aspsnippets.com/post/2009/03/14/Export-GridView-To-WordExcelPDFCSV-in-ASPNet.aspx

Another one, havent tested though.
http://geekswithblogs.net/azamsharp/archive/2006/08/12/87804.aspx

Another one, also havent tested
http://stackoverflow.com/questions/1363169/export-gridview-to-excel-with-rows-formatted-as-text