analyze a file's fragmentation in Windows 7

Question

Is there a way that I can determine the fragmentation of a single file via programmatic means? For example, is there some type of file system API that I can tap into to retrieve this type of information?

Answer 1

I'm just copy and pasting Raymond's reply from the comments, so I've marked it as a community wiki answer.

For C/C++, use FSCTL_GET_RETRIEVAL_POINTERS. For C#, use these wrapper classes.