Lexical grammar

token: keyword; identifier; constant; string-literal; punctuator
preprocessing-token: header-name
only as part of an #include directive; identifier; pp-number; character-constant; string-literal; punctuator; any other character that does not match the other productions
keyword: _Alignas; _Alignof; _Atomic; _Bool; _Complex; _Generic; _Imaginary; _Noreturn; _Pragma; _Static_assert; _Thread_local; auto; break; case; char; const; continue; default; do; double; else; enum; extern; float; for; goto; if; inline; int; long; register; restrict; return; short; signed; sizeof; static; struct; switch; typedef; union; unsigned; void; volatile; while
identifier: identifier-nondigit; identifier identifier-nondigit; identifier digit
identifier-nondigit: nondigit; universal-character-name; other implementation-defined characters
nondigit: any of _ a b c d e f g h i j k l m n o p q r s t u v w x y z A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
digit: any of 0 1 2 3 4 5 6 7 8 9
universal-character-name: \u hex-quad; \U hex-quad hex-quad
hex-quad: hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
constant: integer-constant; floating-constant; enumeration-constant; character-constant
integer-constant: untyped-integer-constant integer-suffix_opt
decimal-constant: nonzero-digit; decimal-constant digit
octal-constant: 0; octal-constant octal-digit
hexadecimal-constant: hexadecimal-prefix hexadecimal-digit; hexadecimal-constant hexadecimal-digit
hexadecimal-prefix: 0x; 0X
nonzero-digit: any of 1 2 3 4 5 6 7 8 9
octal-digit: any of 0 1 2 3 4 5 6 7
hexadecimal-digit: any of 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F
integer-suffix: unsigned-suffix long-suffix_opt; unsigned-suffix long-long-suffix; long-suffix unsigned-suffix_opt; long-long-suffix unsigned-suffix_opt
unsigned-suffix: u; U
long-suffix: l; L
long-long-suffix: ll; LL
floating-constant: decimal-floating-constant; hexadecimal-floating-constant
from C99
decimal-floating-constant: fractional-constant exponent-part_opt floating-suffix_opt; digit-sequence exponent-part floating-suffix_opt
hexadecimal-floating-constant: hexadecimal-prefix hexadecimal-fractional-constant binary-exponent-part floating-suffix_opt; hexadecimal-prefix hexadecimal-digit-sequence binary-exponent-part floating-suffix_opt
fractional-constant: digit-sequence_opt . digit-sequence; digit-sequence .
exponent-part: e sign_opt digit-sequence; E sign_opt digit-sequence
sign: +; -
digit-sequence: digit; digit-sequence digit
hexadecimal-fractional-constant: hexadecimal-digit-sequence_opt . hexadecimal-digit-sequence; hexadecimal-digit-sequence .
binary-exponent-part: p sign_opt digit-sequence; P sign_opt digit-sequence
hexadecimal-digit-sequence: hexadecimal-digit; hexadecimal-digit-sequence hexadecimal-digit
floating-suffix: f; l; F; L
enumeration-constant: identifier
character-constant: ' c-char-sequence '; L' c-char-sequence '; u' c-char-sequence '; U' c-char-sequence '
c-char-sequence: c-char; c-char-sequence c-char
c-char: any member of the source character set except ', \ and the new-line character; escape-sequence
escape-sequence: simple-escape-sequence; octal-escape-sequence; hexadecimal-escape-sequence; universal-character-name
simple-escape-sequence: \'; \"; \?; \\; \a; \b; \f; \n; \r; \t; \v
octal-escape-sequence: \ octal-digit; \ octal-digit octal-digit; \ octal-digit octal-digit octal-digit
hexadecimal-escape-sequence: \x hexadecimal-digit; hexadecimal-escape-sequence hexadecimal-digit
string-literal: encoding-prefix " s-char-sequence_opt "
encoding-prefix: u8; u; U; L
s-char-sequence: s-char; s-char-sequence s-char
s-char: any member of the source character set except ", \ and the new-line character; escape-sequence
punctuator: any of [ ] ( ) { } . -> ++ -- & * + - ~ ! / % << >> < > <= >= == != ^ | && || ? : ; ... = *= /= %= += -= <<= >>= &= ^= |= , # ## <: :> <% %> %: %:%:, matching longer sequences first
header-name: < h-char-sequence >; " q-char-sequence "
h-char-sequence: h-char; h-char-sequence h-char
h-char: any member of the source character set except > and the new-line character
q-char-sequence: q-char; q-char-sequence q-char
q-char: any member of the source character set except " and the new-line character
pp-number: digit; . digit; pp-number digit; pp-number identifier-nondigit; pp-number e sign; pp-number E sign; pp-number p sign; pp-number P sign; pp-number .