Tru64 UNIX
Compaq C Language Reference Manual


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Appendix A
Language Syntax Summary

This section summarizes the syntax of the C language, using the syntax of the ANSI C Standard. Syntactic categories are indicated with bold type, and literal words or characters are indicated with monospaced, nonitalicized type. A colon following a syntactic category introduces its definition. Alternative definitions are listed on separate lines, or are prefaced by the words "one of." An optional element is indicated by the subscript opt. For example, the following line indicates an optional expression enclosed in braces:

{ expressionopt }

The section numbers shown in parentheses refer to the section of the American National Standard for Information Systems-Programming Language C (document number: X3.159-1989) that discusses that part of the language.

A.1.1 Lexical Grammar

A.1.1.1 Tokens

token: (§3.1)

keyword
identifier
constant
string-literal
operator
punctuator

preprocessing-token: (§3.1)

header-name
identifier
pp-number
character-constant
string-literal
operator
punctuator
each nonwhite-space character that cannot be one of the above

A.1.1.2 Keywords

keyword: (§3.1.1) one of


    auto        double      int         struct 
    break       else        long        switch 
    case        enum        register    typedef 
    char        extern      return      union 
    const       float       short       unsigned 
    continue    for         signed      void 
    default     goto        sizeof      volatile 
    do          if          static      while   
 
    _Bool      _Complex (ALPHA ONLY)
 

A.1.1.3 Identifiers

identifier: (§3.1.2)

identifier-nondigit
identifier identifier-nondigit
identifier digit

identifier-nondigit:

nondigit
other implementation-defined characters

nondigit: §3.1.2 one 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: (§3.1.2) one of


    0  1  2  3  4  5  6  7  8  9 

A.1.1.4 Constants

constant: (§3.1.3)

floating-constant
integer-constant
enumeration-constant
character-constant

floating-constant: (§3.1.3.1)

decimal-floating-constant
hexadecimal-floating-constant

decimal-floating-constant

fractional-constant exponent-partopt floating-suffixopt
digit-sequence exponent-part floating-suffixopt

hexadecimal-floating-constant

hexadecimal-prefix hexadecimal-fractional-constant binary-exponent-part floating-suffixopt
hexadecimal-prefix hexadecimal-digit-sequence binary-exponent-part floating-suffixopt

fractional-constant: (§3.1.3.1)

digit-sequenceopt . digit-sequence
digit-sequence .

exponent-part: (§3.1.3.1)

e signopt digit-sequence
E signopt digit-sequence

sign: (§3.1.3.1) one of

+ --

digit-sequence: (§3.1.3.1)

digit
digit-sequence digit

hexadecimal-fractional-constant:

hexadecimal-digit-sequenceopt . hexadecimal-digit-sequence
hexadecimal-digit-sequence .

binary-exponent-part:

p signopt digit-sequence
P signopt digit-sequence

hexadecimal-digit-sequence:

hexadecimal-digit
hexadecimal-digit-sequence hexadecimal-digit

floating-suffix: (§3.1.3.1) one of

f l F L

integer-constant: (§3.1.3.2)

decimal-constant integer-suffixopt
octal-constant integer-suffixopt
hexadecimal-constant integer-suffixopt

decimal-constant: (§3.1.3.2)

nonzero-digit
decimal-constant digit

octal-constant: (§3.1.3.2)

0
octal-constant octal-digit

hexadecimal-constant: (§3.1.3.2)

0x hexadecimal-digit
0X hexadecimal-digit
hexadecimal-constant hexadecimal-digit

nonzero-digit: (§3.1.3.2) one of


    1  2  3  4  5  6  7  8  9 

octal-digit: (§3.1.3.2) one of


    0  1  2  3  4  5  6  7 

hexadecimal-digit: (§3.1.3.2) one 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: (§3.1.3.2)

unsigned-suffix long-suffixopt
long-suffix unsigned-suffixopt

unsigned-suffix: (§3.1.3.2) one of

u U

long-suffix: (§3.1.3.2) one of

l L

enumeration-constant: (§3.1.3.3)

identifier

character-constant: (§3.1.3.4)

' c-char-sequence'
L' c-char-sequence'

c-char-sequence: (§3.1.3.4)

c-char
c-char-sequence c-char

c-char: (§3.1.3.4)

any member of the source character set except
the single-quote ('), backslash (\), or new-line character
escape-sequence

escape-sequence: (§3.1.3.4)

simple-escape-sequence
octal-escape-sequence
hexadecimal-escape-sequence

simple-escape-sequence: (§3.1.3.4) one of


    \'  \"  \?  \\
    \a  \b  \f  \n  \r  \t  \v 

octal-escape-sequence: (§3.1.3.4)

\ octal-digit
\ octal-digit octal-digit
\ octal-digit octal-digit octal-digit

hexadecimal-escape-sequence:(§3.1.3.4)

\x hexadecimal-digit
hexadecimal-escape-sequence hexadecimal-digit

A.1.1.5 String Literals

string-literal: (§3.1.4)

"s-char-sequenceopt"
L"s-char-sequenceopt"

s-char-sequence: (§3.1.4)

s-char
s-char-sequence s-char

s-char: (§3.1.4)

any member of the source character set except
the double-quote ("), backslash (\), or new-line character
escape-sequence

A.1.1.6 Operators

operator: (§3.1.5) one of


    [  ]  (  )  .  -> 
    ++  --  &  *  +  -  ~  !  sizeof 
    /  %  <<  >>  <  >  <=  >=  ==  !=  ^  |  &&  || 
    ?  : 
    =  *=  /=  %=  +=  -=  <<=  >>=  &=  ^=  |= 
    ,  #  ## 

A.1.1.7 Punctuators

punctuator: (§3.1.6) one of


    [  ]  (  )  {  }  *  ,  :  =  ;  ...  # 

A.1.1.8 Header Names

header-name: (§3.1.7)

<h-char-sequence>
"q-char-sequence"

h-char-sequence: (§3.1.7)

h-char
h-char-sequence h-char

h-char: (§3.1.7)

any member of the source character set except
the new-line character and >

q-char-sequence: (§3.1.7)

q-char
q-char-sequence q-char

q-char: (§3.1.7)

any member of the source character set except
the new-line character and "

A.1.1.9 Preprocessing Numbers

pp-number: (§3.1.8)

digit
. digit
pp-number digit
pp-number nondigit
pp-number e sign
pp-number E sign
pp-number .

A.1.2 Phrase Structure Grammar

A.1.2.1 Expressions

primary-expression: (§3.3.1)

identifier
constant
string-literal
( expression )

postfix-expression: (§3.3.2)

primary-expression
postfix-expression [ expression ]
postfix-expression ( argument-expression-listopt )
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression - -

argument-expression-list: (§3.3.2)

assignment-expression
argument-expression-list , assignment-expression

unary-expression: (§3.3.3)

postfix-expression
++ unary-expression
- - unary-expression
unary-operator cast-expression
sizeof unary-expression
sizeof ( type-name )

unary-operator: (§3.3.3) one of


    &  *  +  -  ~  ! 

cast-expression: (§3.3.4)

unary-expression
( type-name ) cast-expression

multiplicative-expression: (§3.3.5)

cast-expression
multiplicative-expression * cast-expression
multiplicative-expression / cast-expression
multiplicative-expression % cast-expression

additive-expression: (§3.3.6)

multiplicative-expression
additive-expression + multiplicative-expression
additive-expression - multiplicative-expression

shift-expression: (§3.3.7)

additive-expression
shift-expression << additive-expression
shift-expression >> additive-expression

relational-expression: (§3.3.8)

shift-expression
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
relational-expression >= shift-expression

equality-expression: (§3.3.9)

relational-expression
equality-expression == relational-expression
equality-expression != relational-expression

AND-expression: (§3.3.10)

equality-expression
AND-expression & equality-expression

exclusive-OR-expression: (§3.3.11)

AND-expression
exclusive-OR-expression ^ AND-expression

inclusive-OR-expression: (§3.3.12)

exclusive-OR-expression
inclusive-OR-expression | exclusive-OR-expression

logical-AND-expression: (§3.3.13)

inclusive-OR-expression
logical-AND-expression && inclusive-OR-expression

logical-OR-expression: (§3.3.14)

logical-AND-expression
logical-OR-expression || logical-AND-expression

conditional-expression: (§3.3.15)

logical-OR-expression
logical-OR-expression ? expression : conditional-expression

assignment-expression: (§3.3.16)

conditional-expression
unary-expression assignment-operator assignment-expression

assignment-operator: (§3.3.16) one of


    =  *=  /=  %=  +=  -=  <<=  >>=  &=  ^=  |= 

expression: (§3.3.17)

assignment-expression
expression , assignment-expression

constant-expression: (§3.4)

conditional-expression

A.1.2.2 Declarations

declaration: (§3.5)

declaration-specifiers init-declarator-listopt ;

declaration-specifiers: (§3.5)

storage-class-specifier declaration-specifiersopt
type-specifier declaration-specifiersopt
type-qualifier declaration-specifiersopt

init-declarator-list: (§3.5)

init-declarator
init-declarator-list , init-declarator

init-declarator: (§3.5)

declarator
declarator = initializer

storage-class-specifier: (§3.5.1)

typedef
extern
static
auto
register

type-specifier: (§3.5.2)

void
char
short
int
long
float
double
signed
unsigned _Bool _Complex (ALPHA ONLY)


struct-or-union-specifier
enum-specifier
typedef-name

struct-or-union-specifier: (§3.5.2.1)

struct-or-union identifieropt { struct-declaration-list }
struct-or-union identifier

struct-or-union: (§3.5.2.1)

struct
union

struct-declaration-list: (§3.5.2.1)

struct-declaration
struct-declaration-list struct-declaration

struct-declaration: (§3.5.2.1)

specifier-qualifier-list struct-declarator-list ;


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