Even if your IDE would type your entire programs for you, you would still know the syntax of the language just because I am 100% sure you have actually read more code than you ever wrote. And do note that even in C there is not a single official loop syntax -- a while (get_next())-like thing is a perfectly valid loop in C. All of them valid answers -- I used the word "sequence" and not "C array" for a reason.

And if I start showing them an EBNF grammar for the language, now that's TWO languages that you will show you don't remember rather than one. I find this even more absurd; you don't remember anything of the syntax of the language you used at work for years, but you think you can rediscover it from the FORMAL language specification in a whiteboard?