TIOBE - C Coding Standard
|Synopsis:||Trigraphs shall not be used.|
|Trigraphs quite apart from their non-portability to pre-ANSI environments, look very confusing. Avoiding adjacent question marks eliminates any possible confusion with trigraphs. Note in particular the, once common, practice of using ? as a place holder in a string is very dangerous.
char date = "??-??-??";
/* This is actually replaced with: */
char date = "~~??";