How do I form complete URLs from incomplete URLs found in a web page?

Answer 1

If you mean server-side, you can use ResolveUrl():

string url = ResolveUrl("~/questions");

Answer 2

I dont understand what you mean by "resolve" in this context, but you can try inserting a base html element. Since you asked how the browser would handle it.

"The <base> tag specifies a default address or a default target for all links on a page."

http://www.w3schools.com/TAGS/tag_base.asp

Answer 3

You mean like this?

Uri baseUri = new Uri("http://www.contoso.com");
Uri myUri = new Uri(baseUri, "catalog/shownew.htm");

Console.WriteLine(myUri.ToString());

Sample comes from http://msdn.microsoft.com/en-us/library/9hst1w91.aspx