Identifiers

An identifier is an arbitrarily long sequence of digits, underscores, lowercase and uppercase Latin letters, and most Unicode characters.

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
CWG 1440	C++11	decltype expressions preceding :: could denote any type	can only denote classor enumeration types
CWG 1963	C++11	implementation-defined characters other than digits, non-digitsand universal character names could be used in an identifier	prohibited
CWG 2521	C++11	the identifier in user-defined-string-literal ofa literal operator was reserved as usual	the rules are different
CWG 2771	C++98	&a was not transformed into &this->a in class contexts	it is transformed
CWG 2777	C++20	the type of an identifier expression was unclearif it names a template parameter object	made clear
CWG 2818	C++98	predefined macro names are reserved	they are not reserved