5 Lexical conventions [lex]

5.9 Preprocessing numbers [lex.ppnumber]

pp-number:
	digit
	. digit
	pp-number digit
	pp-number identifier-nondigit
	pp-number ' digit
	pp-number ' nondigit
	pp-number e sign
	pp-number E sign
	pp-number p sign
	pp-number P sign
	pp-number .

Preprocessing number tokens lexically include all integer literal tokens and all floating literal tokens.

A preprocessing number does not have a type or a value; it acquires both after a successful conversion to an integer literal token or a floating literal token.