问题
We all know about the historical curiosity that is digraphs and trigraphs, but with all the changes made to C++ in recent years I'm curious: are they valid C++14? How about C++17?
回答1:
Trigraphs are currently valid, but won't be for long!
Trigraphs were proposed for deprecation in C++0x, which was released as C++11. This was opposed by IBM, speaking on behalf of itself and other users of C++, and as a result trigraphs were retained in C++0x. Trigraphs were then proposed again for removal (not only deprecation) in C++17. This passed a committee vote, and trigraphs are expected to be removed from C++17 despite the opposition from IBM and others. Existing code that uses trigraphs can be supported by translating from the physical source files (parsing trigraphs) to the basic source character set that does not include trigraphs. [Wikipedia]
Digraphs, however, are sticking around for now.
来源：https://stackoverflow.com/questions/27678297/are-trigraphs-still-valid-c