C# Development How To Notes
Tilde (~) and Virtual Paths with ASP.NET
Introducing the Tilde (~)
In an ASP.NET application the framework controls recognise a
tilde ('~') as a shortcut to the root of the application's virtual
directory. So the framework will expand a tilde to the value of
So for example in the code behind
will redirect to the page "Login.aspx" in the root of the
will redirect to the page "Users.aspx" in the folder "Admin" off
These will resolve to the correct location,
regardless of which folder it is called from.
<asp:Image ID="image1" runat="server" ImageUrl="~/images/logo.gif"/>
on a page the framework will substitute the correct path
to "images/log.gif" where the folder "images" is off the root.
Why use a tilde (~) instead of a relative path?
So why use a tilde instead or a relative path? In many cases you
can use a relative path instead of a tilde. Using a tilde is often
clearer because it makes it clearer what (where!) is being
There are also situations where a tilde is the only viable thing
to use. This is particularly true when using your own components,
controls and class libraries, where with the tilde you can rely on the framework to
resolve to the correct relative path.
Outside the framework - Getting the
There are times when you might need an absolute URL, such as when
passing a URL to a non-framework component.
There are a few options:
Option 1. Page.ResolveUrl
Page.ResolveUrl will return a URL relative to the root of the
website. So for example:
where "/wwwroot" happens to be the root of the project I am
working in, so that will be different for you.
This can be used for any URLs which need to work within the
Option 2. Page.ResolveClientUrl
Page.ResolveClientUrl will return a URL relative to the current
page. So for example:
will return "Admin/Users.aspx" if called from a page in the root
folder, but if it were called from say "Admin/Clients.aspx" - which
note is in the same "Admin" folder - then it will return simply "Users.aspx".
This can be used for any URLs which need to work within within
Option 3. Generate an absolute URL
If you are passing a URL to a different website then you may need
the full URL. This requires a little bit of code:
public string GetAbsoluteUrl(string page)
else if (VirtualPathUtility.IsAbsolute(page))
HttpContext.Current.Request.Url.Scheme + "://"
This will return the full URL of the page (or resource) passed to
it, making the assumption that the page (or resource) is part of the
website and that if the current page is secure then the URL to the
page should be secure.
About the author: Brian Cryer
is a dedicated software developer and webmaster. For his day job he
develops websites and desktop applications as well as providing
IT services. He moonlights as a technical author and consultant.