..given an URL as input (C programming language). (Sitemap specifications from sitemap.org).
A:
As stated in the comments by apphacker we don't really know what you're trying to do. If you are planning on just scraping links from a html website then I would recommend some sort of lexical scanner generator: like flex.
If you are getting a website url as input then you are going to need to use the some networking code to read the webpages. If you don't know anything about networking in C then I would recommend googling beej's guides and going from there.
If you are just getting a straight XML file as your tags suggest then once again I would recommend flex if you absolutely must use C. If you don't have to use C then I would recommend Perl or Python; they are probably better suited to the job.
Either way we need you to give us more information but I hope that helps for now.
Robert Massaioli
2009-04-18 03:03:44