How to access inetpub root folder using programatically in sharepoint

Here i have mentioned how to access inetpub root folder using object model.

using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;

string filename = web.Site.WebApplication.IisSettings[SPUrlZone.Default].Path.FullName.ToString() + @"\_app_bin\layouts.sitemap";

it will give filename like "C:\Inetpub\wwwroot\wss\VirtualDirectories\5858\_app_bin\layouts.sitemap"