> Well, OP asked for source of truth. Nothing comes as close as the standard itself. An unfortunate reality is that standards are not always strictly followed

> Well, OP asked for source of truth. Nothing comes as close as the standard itself. An unfortunate reality is that standards are not always strictly followed (whether intentionally or not). C is almost certainly better about following the standards than other pieces of tech (notably web browsers), but I doubt the C compilers are perfectly compliant if you look hard enough.