Proper https redirects solution?

Can anyone supply a foolproof 301 redirect that i can add to htaccess that will redirect all url requests to the https://www. equivalent

For example:

Code:

http://www.example.com/about -> https://www.example.com/about
http://example.com/about -> https://www.example.com/about
https://example.com/about -> https://www.example.com/about

We are hosting more and more sites using cPanel, so it would be useful to have a solution for all of these.