SyntaxofTheCProgrammingLanguage.doc

Syntax of The C Programming Language
Cross-Refferences
1. ASCII::= See http://www.csci.csusb.edu/dick/samples/comp.text.ASCII.html
Used_in The definition of C++ [ c++.syntax.html ]
Used_in The definition of Java [ java.syntax.html ]
Notation
This uses my XBNF Extended BNF Notation where "|" indicates "or", "(...)" indicates priority. For more information see [ intro_ebnf.html ]
The following abbreviations are also used:

1. O(_)::= 0 or 1 occurrences,
2. N(_)::= 1 or more occurrence
3. L(_)::= a comma separated list
4. #(_)::= 0 or more occurrences.
5. S(E,Op)::=serial_operator_expression(E, Op)
6. serial_operator_expression(E,Op)::= E #(Op E).
S(E,Op) = E Op E Op E Op ... E

It also uses the following shorthand
Lexemes
7. identifier::=nondigit #(nondigit | digit),
8. nondigit::="_" | "a" | "A" | "b" | "B" | "c" | "C" | "d" | "D" | "e" | "E" | "f" | "F" | "g" | "G" | "h" | "H" | "i" | "I" | "j" | "J" | "k" | "K" | "l" | "L" | "m" | "M" | "n" | "N" | "o" | "O" | "p" | "P" | "q" | "Q" | "r" | "R" | "s" | "S" | "t" | "T" | "u" | "U" | "v" | "V" | "w" | "W" | "x" | "X" | "y" | "Y" | "z" | "Z",
9. digit::="0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9",
10. punctuator::="[" | "]" | "(" | ")" | "{" | "}" | "*" | "," | ":" | "=" | ";" | "..." | "#",
11. operator::="[" | "]" | "(" | ")" | "." | "->" | "++" | "--" | "&" | "*" | "+" | "-" | "~" | "!" | "sizeof" | "/" | "%" | "<<" | ">>" | "<" | ">" | "<=" | ">=" | "==" | "!=" | "^" | "|" | "&&" | "||" | "?" | ":" | "=" | "*=" | "/=" | "%=" | "+=" | "-=" | "<<=" | ">>=" | "&=" | "^=" | "||=" | "," | "#" | "##",
12. infix::= "->" | "&" | "*" | "+" | "-" | "/" | "%" | "<<" | ">>" | "<" | ">" | "<=" | ">=" | "==" | "!=" | "^" | "|" | "&&" | "||" | "=" | "*=" | "/=" | "%=" | "+=" | "-=" | "<<=" | ">>=" | "&=" | "^=" | "||=" | "," ,
13. prefix::= "++" | "--" | "&" | "*" | "+" | "-" | "~" | "!" | "sizeof" ,
14. postfix::= "++" | "--",
15. integer_suffix::=#(unsigned_suffix) | #(long_suffix),
16. unsigned_suffix::="u" | "U",
17. long_suffix::="l" | "L",
18. sign::="+" | "-",
19. octal_constant::="0" #(octal_digit),
20. octal_digit::="0" | "1" | "2" | "3" | "4" | "5" | "6" | "7",
21. hex_constant::=("0x" | "0X") (hex_digit),
22. hex_digit::="0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" | "a" | "b" | "c" | "d" | "e" | "f" | "A" | "B" | "C" | "D" | "E" | "F",
23. decimal_constant::=non_zero_digit #(digit),
24. non_zero_digit::="1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9",
25. integer_constant::=(decimal_constant | octal_constant | hex_constant) | integer_suffix,
26. float_suffix::="f" | "l" | "F" | "L",
27. fraction::=#digit "." digit #digit,
28. exponent_part::=("e" | "E") sign #(digit),
29. float_constant::=fraction (exponent_part|) (float_suffix|)|(decimal_constant (exponent_part|) float_suffix,
30. enumeration_constant::=identifier,
31. char_constant::=char~(double_quote|eoln|backslash)| escape_sequence,
32. escape_sequence::=backslash (char | "0" #octal_digit |"0x"#hexadecimal_digit),
33. character_constant::="'" char_constant"'" ,
constant :=::=float_constant | integer_constant | enumeration_constant | character_constant,
34. string__char::=char~(double_quote|eoln|backslash)| escape_sequence,
35. string_literal::=double_quote #(string_char) double_quote,
. . . . . . . . . ( end of section Lexemes) <<Contents | End>>
Expressions
Expressions are made up by applying operators to primary_expressions.
36. primary_expression::= variable | constant | string_literal | "(" expression ")",
37. variable::= identifier & declared and in scope of declaration.
38. argument_list::=List(assignment_expression),
Operators
Symbol
See
"("... ")"
primary_expression cast_expression function_call
"."
part of a structure
"-"
additive_expression unary_expression
"->"
part of a pointed at structure
"--"
unary_expression postfix_expression
"-="
assignment_expression
"&"
AND_expression bitwise Boolean
"&="
assignment_expression
"&"
address_of unary_expression
"&&"
logical_AND_expression
"*"
multiplicative_expression contents of pointer unary_expression
"*="
assignment_expression
"+"
additive_expression unary_expression
"++"
unary_expression postfix_expression
"+="
assignment_expression
"~"
bitwise negation prefix
"!"
logical negation prefix
"!="
equality_expression
"sizeof"
unary_expression
"/"
multiplicative_expression divide
"/="
assignment_expression
"%"
multiplicative_expression mod
"%="
assignment_expression
"<"
relational_expression
"<<"
shift_expression left
"<<="
assignment_expression
"<="
relational_expression
">"
relational_expression
">>"
shift_expression right
">="
relational_expression
">>="
assignment_expression
"=="
equality_expression
"="
assignment_expression
"^"
XOR_expression exclusive-or bitwise
"^="
assignment_expression
"|"
OR_expression bitwise or
"||"
logical_OR_expression
"||="
assignment_expression
..."?"... ":"...
conditional_expression
","
expression (discard previous value)
Arithmetic
39. post_fix::="++" | "--",
40. post_fix_expression::=(primary_expression) #(post_fix),
41. unary_operator::="&" | "*" | "+" | "-" | "!" | "-",
42. pre_fix::="++" | "--" | "sizeof",
43. unary_expression::=#(pre-fix) post_fix_expression | unary_operator cast_expression | "sizeof" "(" type_name")",
44. cast_expression::=#(type_name) unary_expression. This implies that casts are done after doing post-fix operations..
45. multiplicative_expression::=S(cast_expression, multiplicative_operator). [ serial_operator_expression ]
The rule above means that 'casts' are done before multiplication and division, and that multiplication and division are done from left to right.
46. multiplicative_operator::="*" | "%" | "/",
47. additive_expression::=S(multiplicative_expression, additive_operator). This means that addition and subtraction occurs after multiplication and from left to right.
48. additive_operator::="+" | "-",
Shifts
49. shift_expression::=S(additive_expression, shift_operator),
50. shift_operator::=">>" | "<<", "<<" is left shift of bits (multiply by 2), and ">>" is the reverse and divides by 2.
Relations
51. relational_expression::= S(shift_expression, relational_operator),
52. relational_operator::="<" | ">" | "<=" | ">=",
53. equality_expression::=S(relational_expression, equality_operator),
54. equality_operator::="==" | "!=",
Bitwise Expressions
These use the lowest level machine code operations that manipulate the bits in words. They are very fast and powerful. They are mostly used in system programming: drivers, operating systems, compilers, interpreters, shells, ... . They are also a very fast and tight coding for subsets of small sets: one bit per element has 1 for membership and 0 for nonmembership. For example if a class can meet on any collection of the 5 working days in a week (Monday=1, ..., Friday=5) then
FRWTM
10101 = MWF
Decimal
Binary (last 4 bits/ 1 byte)
0
0000
1
0001
2
0010
3
0011
4
0100
5
0101
6
0110
7
0111
8
1000
55. AND_expression::=S(equality_expression, and_operator),
56. and_operator::="&", This operator takes each bit in the value of its arguments in turn to calculate the bit in the answer. A bit is 1 if and only if both arguments have bits in that place that are 1.
Decimal
Binary
3
0011
5
0101
3&5
0001
57. XOR_expression::=S(AND_expression, XOR_operator),
58. XOR_operator::="^", XOR is short for eXclusive-OR. The n'th bit in the value is 1 precisly when the n'th bits in the two arguments are different.
Decimal
Binary
3
0011
5
0101
3^5
0110
59. OR_expression::=S(XOR_expression, OR_operator),
60. OR_operator::="|", This operator takes each bit in the value of its arguments in turn to calculate the bit in the answer. The n'th bit is 1 if either n'th bits is 1.
Decimal
Binary
3
0011
5
0101
3|5
0111
61. Logical Expressions
62. In C, logical false is reresented by any zero value and true by any nonzero value. Here is a list of operators
1. and::="&&".
2. or::="||",
3. not::="!",

63. logical_AND_expression::=S(OR_expression, logical_AND_operator),
64. logical_AND_operator::=and, A&&B is true precisely when both A and B evaluate to be true. If A evaluates to false, B is not evaluated.
65. logical_OR_expression::=S(logical_AND_expression, logical_OR_operator),
66. logical_OR_operator::=or, A||B is true if A evaluates to be true, or when A is false and B evaluates to be true. If both evaluate to false (zero) then A||B is false.
Conditional Expressions
67. conditional_expression::=logical_OR_expression | logical_OR_expression "?" expression ":" conditional_expression,
Assignment Statements
68. assignment_expression::=S(unary_expression, assignment_operator),
69. assignment_operator::="=" | "*=" | "/=" | "%=" | "+=" | "<<=" | ">>=" | "&=" | "^=" | "|=",
70. expression::=List(assignment_expression ),
71. constant_expression::=conditional_expression,
. . . . . . . . . ( end of section Expressions) <<Contents | End>>
Declarations
72. declaration::=declaration_specifier | declarator_list,
73. declarator_list::=List(declarator_initialized),
74. declaration_specifier::=(storage_class | type_specifier | type_qualifier),
75. storage_class::="typedef" | "extern" | "static" | "auto" | "register",
Types
76. type_specifier::="void" | "char" | "short" | "int" | "long" | "float" | "double" | "signed" | "unsigned" | struct_union_specifier | enumeration_specifier | typedef_name,
77. type-qualifier::="const" | "volatile",
78. typedef_name::=identifier,
Initialization
79. initializer::=assignment_expression | initializer_list,
80. initializer_list::=List(initializer),
81. declarator_initialized::=declarator ("=" initializer),
Structs and Unions
82. structure_declarator::=declarator | declarator ":" constant_expression,
83. structure_declarator_list::=List(structure_declarator),
84. structure_declaration::=(type_specifier | type_qualifier) structure_declarator_list ";" ,
85. struct_union_specifier::=struct_union identifier | struct_union identifier "{"structure_declarator_list "}",
86. struct_union::=( "struct" | "union" ),
Enums
87. enumeration_value::=enumeration_constant ("=" constant_expression|)
88. enumeration_list::=List(enumeration_value ),
89. enumeration_specifier::=enumeration_identifier | "enum" identifier "{"enumeration_list"}",
Functions
90. function_definition::=declaration_specifier declarator | declaration_list | compound_statement,
91. parameter_declaration::=#declaration_specifier declarator | abstract_declarator,
92. parameter_list::=List(parameter_declaration) (",..."|),
Pointers
93. pointer::=#( "*" | #type_qualifier),
94. declarator::=pointer | direct_declarator,
Functions and Arrays
95. post_declarator::="["constant_expression"]" | "("parameter_list")" | "("identifier_list")"
96. direct_declarator::=identifier | "("declarator")" | direct_declarator post_declarator,
97. abstract_declarator::=pointer | pointer direct_abstract_declarator,
98. direct_abstract_declarator::= "(" abstract_declarator ")" | O( direct_abstract_declarator) O("[" O(constant_expression) "]" | "(" O(parameter_list) ")" ),
. . . . . . . . . ( end of section Declarations) <<Contents | End>>
Statements
99. statement::=labeled_statement | compound_statement | expression_statement | selection_statement | iteration_statement | jump_statement
Branch
100. jump_statement::="goto" identifier";" | "continue" ";" | "break;" | "return" expression ";",
Structured
101. loop::=iteration_statement.
102. iteration_statement::="while" "("expression")" statement | "do" statement "while" "("expression")" ";" | for_statement.
103. for_statement::="for" "("expression ";" expression ";" expression")" statement,
104. selection_statement::=if_statement | "switch" "("expression")" statement,
105. if_statement::="if ("expression")" statement | "if" "("expression")" statement "else" statement.
106. expression_statement::= expression ";",
107. labeled_statement::=identifier ":" statement | "case" constant_expression ":" statement | "default" ":" statement,
Compound
108. compound_statement::=block | "{" #statement "}",
109. block::="{" declaration #declaration #statement "}",
. . . . . . . . . ( end of section Statements) <<Contents | End>>
Pre-Processor Commands
110. preprocess_token::=identifier | constant | string_literal | operator | punctuator | each Non-white space not one of the previous,
111. header_char::=any character except new_line | and | >,
112. header_name::=#(header_char),
113. new_line::=new_line character,
114. Left_paren::=left parenthesis with no white space before it,
115. control_line::="#include" (#(preprocess_token | header_name) new_line | "#define" identifier #(preprocess_token) new_line | "#define" identifier left_paren identifier_list #(preprocess_token) new_line, | "#undef" identifier new_line | "#line" preprocess_token new_line | "#error" preprocess_token new_line | "#pragma" preprocess_token new_line | "#"new_line,
116. endif_line::="#endif" new_line,
117. elif_group::="#elif" constant_expression new_line pp_group,
118. else_group::="#else" new_line pp_group,
119. if_group::=("#if" constant_expression | "#ifdef" identifier | "#ifndef" identifier) new_line pp_group,
120. if_part::=if_group #(elif_group) else_group endif_line,
121. pp_part::=#preprocess_token new_line | if_part | control_line,
122. pp_group::=#(pp_part),
. . . . . . . . . ( end of section Pre-Processor Commands) <<Contents | End>>
. . . . . . . . . ( end of section Syntax of The C Programming Language) <<Contents | End>>
End