I've never understood the reluctance. The only reader who could be puzzled by
!!
is one who has never seen it before. So he asks a colleague who tells him "you use it to convert an integer to 1 or 0" and now he knows the idiom forever. I constantly get dinged on this in code reviews (different companies each time) and the reviewers constantly cite an arbitrary employee-to-be-hired-in-the-future as the one who won't know about
!!
but can never point to anyone who actually doesn't know, or who, after having it explained, won't remember it. (Example is old though: not needed in modern C++) —
davidbak 44 secs ago