HOW TO BECOME PROFICIENT IN C

So I claimed I was proficient in a number of languages on my resume, all of which I've barely used.

I think I can get away with some of it but I really think I need to know how to use C and Python well for the job. He said the job might require C# which is close enough to core C.

How do I become proficient with these languages in a week or so?

>>2

This book is overhyped and useless for non-Scheme programmers. The obscure and non-intuitive syntax(with plenty of parenteheses) of Lisp + heavy abuse of recursion means people learn bad coding habits. If you want to learn practical programming use a book suited to your language of choice, or a language reference/manual.