Use this code:
HttpContext.Current.Server.MapPath("~")
Detailed Reference:
Server.MapPath specifies the relative or virtual path to map to a physical directory.
Server.MapPath(".") returns the current physical directory of the
file (e.g. aspx) being executedServer.MapPath("..") returns the parent directoryServer.MapPath("~") returns the physical path to the root of the
applicationServer.MapPath("/") returns the physical path to the root of the
domain name (is not necessarily the same as the root of the
application)An example:
Let's say you pointed a web site application (http://www.example.com/) to
C:\Inetpub\wwwroot
and installed your shop application (sub web as virtual directory in IIS, marked as application) in
D:\WebApps\shop
For example, if you call Server.MapPath in following request:
http://www.example.com/shop/products/GetProduct.aspx?id=2342
then:
Server.MapPath(".") returns D:\WebApps\shop\products
Server.MapPath("..") returns D:\WebApps\shop
Server.MapPath("~") returns D:\WebApps\shop
Server.MapPath("/") returns C:\Inetpub\wwwroot
Server.MapPath("/shop") returns D:\WebApps\shop
If Path starts with either a forward (/) or backward slash (), the MapPath method returns a path as if Path were a full, virtual path.
If Path doesn't start with a slash, the MapPath method returns a path relative to the directory of the request being processed.
Note: in C#, @ is the verbatim literal string operator meaning that the string should be used "as is" and not be processed for escape sequences.
Footnotes
Server.MapPath(null) and Server.MapPath("") will produce this effect too.