How to get Current Web Url using .net Csom in sharepoint

Hi dear,

Currently i am running through an issue that i need to get the current Web url in SharePoint using .net Csom...

i don't want to pass the url in client context like below

Client Context context = new ClientContext("http://najbsys2:1990/GeneralExpense/");

i want to get it dynamically as in server side object mode like below

SpContext.current.web.url

anybody has solution please provide me its urgent ,,i have gone through various web sites but i didn't get solution anywhere