cppdraft_translate/cppdraft/lex/universal/char.md

[lex.universal.char]

# 5 Lexical conventions [[lex]](./#lex)

## 5.3 Characters [[lex.char]](lex.char#lex.universal.char)

### 5.3.2 Universal character names [lex.universal.char]

[n-char:](#nt:n-char "5.3.2 Universal character names [lex.universal.char]")  
any member of the translation character set except the U+007d right curly bracket or new-line character

[n-char-sequence:](#nt:n-char-sequence "5.3.2 Universal character names [lex.universal.char]")  
[*n-char*](#nt:n-char "5.3.2 Universal character names [lex.universal.char]") [*n-char-sequence*](#nt:n-char-sequence "5.3.2 Universal character names [lex.universal.char]")opt

[named-universal-character:](#nt:named-universal-character "5.3.2 Universal character names [lex.universal.char]")  
\N{ [*n-char-sequence*](#nt:n-char-sequence "5.3.2 Universal character names [lex.universal.char]") }

[hex-quad:](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]")  
[*hexadecimal-digit*](lex.icon#nt:hexadecimal-digit "5.13.2 Integer literals [lex.icon]") [*hexadecimal-digit*](lex.icon#nt:hexadecimal-digit "5.13.2 Integer literals [lex.icon]") [*hexadecimal-digit*](lex.icon#nt:hexadecimal-digit "5.13.2 Integer literals [lex.icon]") [*hexadecimal-digit*](lex.icon#nt:hexadecimal-digit "5.13.2 Integer literals [lex.icon]")

[simple-hexadecimal-digit-sequence:](#nt:simple-hexadecimal-digit-sequence "5.3.2 Universal character names [lex.universal.char]")  
[*hexadecimal-digit*](lex.icon#nt:hexadecimal-digit "5.13.2 Integer literals [lex.icon]") [*simple-hexadecimal-digit-sequence*](#nt:simple-hexadecimal-digit-sequence "5.3.2 Universal character names [lex.universal.char]")opt

[universal-character-name:](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]")  
\u [*hex-quad*](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]")  
\U [*hex-quad*](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]") [*hex-quad*](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]")  
\u{ [*simple-hexadecimal-digit-sequence*](#nt:simple-hexadecimal-digit-sequence "5.3.2 Universal character names [lex.universal.char]") }  
[*named-universal-character*](#nt:named-universal-character "5.3.2 Universal character names [lex.universal.char]")

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lex.tex#L467)

The [*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]") construct provides a way to name any
element in the translation character set using just the basic character set[.](#1.sentence-1)

If a [*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]") outside
the [*c-char-sequence*](lex.ccon#nt:c-char-sequence "5.13.3 Character literals [lex.ccon]"), [*s-char-sequence*](lex.string#nt:s-char-sequence "5.13.5 String literals [lex.string]"), or[*r-char-sequence*](lex.string#nt:r-char-sequence "5.13.5 String literals [lex.string]") of a [*character-literal*](lex.ccon#nt:character-literal "5.13.3 Character literals [lex.ccon]") or[*string-literal*](lex.string#nt:string-literal "5.13.5 String literals [lex.string]") (in either case, including within a [*user-defined-literal*](lex.ext#nt:user-defined-literal "5.13.9 User-defined literals [lex.ext]"))
corresponds to a control character or to a character in the basic character set,
the program is ill-formed[.](#1.sentence-2)

[*Note [1](#note-1)*:

A sequence of characters resembling a [*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]") in an[*r-char-sequence*](lex.string#nt:r-char-sequence "5.13.5 String literals [lex.string]") ([[lex.string]](lex.string "5.13.5 String literals")) does not form a[*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]")[.](#1.sentence-3)

— *end note*]

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lex.tex#L483)

A [*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]") of the form \u [*hex-quad*](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]"),\U [*hex-quad*](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]") [*hex-quad*](#nt:hex-quad "5.3.2 Universal character names [lex.universal.char]"), or\u{[*simple-hexadecimal-digit-sequence*](#nt:simple-hexadecimal-digit-sequence "5.3.2 Universal character names [lex.universal.char]")} designates the character in the translation character set
whose Unicode scalar value is the hexadecimal number represented by
the sequence of [*hexadecimal-digit*](lex.icon#nt:hexadecimal-digit "5.13.2 Integer literals [lex.icon]")*s* in the [*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]")[.](#2.sentence-1)

The program is ill-formed if that number is not a Unicode scalar value[.](#2.sentence-2)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/lex.tex#L494)

A [*universal-character-name*](#nt:universal-character-name "5.3.2 Universal character names [lex.universal.char]") that is a [*named-universal-character*](#nt:named-universal-character "5.3.2 Universal character names [lex.universal.char]") designates the corresponding character
in the Unicode Standard (chapter 4.8 Name)
if the [*n-char-sequence*](#nt:n-char-sequence "5.3.2 Universal character names [lex.universal.char]") 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[.](#3.sentence-1)

[*Note [2](#note-2)*:

These aliases are listed in
the Unicode Character Database's NameAliases.txt[.](#3.sentence-2)

None of these names or aliases have leading or trailing spaces[.](#3.sentence-3)

— *end note*]