Want to get facebook user name/email on the bases of facebook id

I want to know, how someone find the username/email address of facebook by using facebook id.

 

You cannot get the email address. It would be a violation of Facebook's privacy policy.

You can however use the id to go to the profile page, and see the username if the user has set a vanity url. Its different from their email address though.

 

Yeah harvest their ids that's the only option