cppdraft_translate/cppdraft/lex/universal/char.md

[lex.universal.char]

5 Lexical conventions [lex]

5.3 Characters [lex.char]

5.3.2 Universal character names [lex.universal.char]

n-char:
any member of the translation character set except the U+007d right curly bracket or new-line character

n-char-sequence:
n-char n-char-sequenceopt

named-universal-character:
\N{ n-char-sequence }

hex-quad:
hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit

simple-hexadecimal-digit-sequence:
hexadecimal-digit simple-hexadecimal-digit-sequenceopt

universal-character-name:
\u hex-quad
\U hex-quad hex-quad
\u{ simple-hexadecimal-digit-sequence }
named-universal-character

1

#

The universal-character-name construct provides a way to name any element in the translation character set using just the basic character set.

If a universal-character-name outside the c-char-sequence, s-char-sequence, orr-char-sequence of a character-literal orstring-literal (in either case, including within a user-defined-literal) corresponds to a control character or to a character in the basic character set, the program is ill-formed.

[Note 1:

A sequence of characters resembling a universal-character-name in anr-char-sequence ([lex.string]) does not form auniversal-character-name.

— end note]

2

#

A universal-character-name of the form \u hex-quad,\U hex-quad hex-quad, or\u{simple-hexadecimal-digit-sequence} designates the character in the translation character set whose Unicode scalar value is the hexadecimal number represented by the sequence of hexadecimal-digits in the universal-character-name.

The program is ill-formed if that number is not a Unicode scalar value.

3

#

A universal-character-name that is a named-universal-character designates the corresponding character in the Unicode Standard (chapter 4.8 Name) if the n-char-sequence is equal to its character name or to one of its character name aliases of type “control”, “correction”, or “alternate”; otherwise, the program is ill-formed.

[Note 2:

These aliases are listed in the Unicode Character Database's NameAliases.txt.

None of these names or aliases have leading or trailing spaces.

— end note]