. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv 1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Normative references . . . . . . . . . . . . . . . . . . . . . . . 3. Terms, definitions, and symbols 4. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Environment 5.1 Conceptual models 5.1.1 Translation environment . 5.1.2 Execution environments 5.2 Environmental considerations 5.2.1 Character sets 5.2.2 Character display semantics 5.2.3 Signals and interrupts . . 5.2.4 Environmental limits 6. Language . . . . . . . . . . . . . . . . . 6.1 Notation . . . . . . . . . . . . . . . 6.2 Concepts 6.2.1 Scopes of identifiers 6.2.2 Linkages of identifiers . . . . . . 6.2.3 Name spaces of identifiers 6.2.4 Storage durations of objects 6.2.5 Types 6.2.6 Representations of types . . . . . 6.2.7 Compatible type and composite type 6.3 Conversions 6.3.1 Arithmetic operands 6.3.2 Other operands 6.4 Lexical elements 6.4.1 Keywords . . . . . . . . . . . 6.4.2 Identifiers . . . . . . . . . . . 6.4.3 Universal character names 6.4.4 Constants . . . . . . . . . . . 6.4.5 String literals 6.4.6 Punctuators . . . . . . . . . . 6.4.7 Header names 6.4.8 Preprocessing numbers 6.4.9 Comments 6.5 Expressions iii 6.5.1 Primary expressions 6.5.2 Postfix operators . . . . . 6.5.3 Unary operators 6.5.4 Cast operators . . . . . . 6.5.5 Multiplicative operators 6.5.6 Additive operators 6.5.7 Bitwise shift operators . . . 6.5.8 Relational operators . . . . 6.5.9 Equality operators Bitwise AND operator . . . Bitwise exclusive OR operator Bitwise inclusive OR operator Logical AND operator . . . Logical OR operator Conditional operator Assignment operators . . . Comma operator . . . . . 6.6 Constant expressions . . . . . . . 6.7 Declarations 6.7.1 Storage-class specifiers 6.7.2 Type specifiers . . . . . . 6.7.3 Type qualifiers . . . . . . 6.7.4 Function specifiers 6.7.5 Declarators 6.7.6 Type names . . . . . . . 6.7.7 Type definitions 6.7.8 Initialization 6.8 Statements and blocks 6.8.1 Labeled statements 6.8.2 Compound statement 6.8.3 Expression and null statements 6.8.4 Selection statements 6.8.5 Iteration statements . . . . 6.8.6 Jump statements 6.9 External definitions 6.9.1 Function definitions . . . . 6.9.2 External object definitions 6.10 Preprocessing directives 6.10.1 Conditional inclusion 6.10.2 Source file inclusion 6.10.3 Macro replacement . . . . 6.10.4 Line control . . . . . . . 6.10.5 Error directive . . . . . . 6.10.6 Pragma directive . . . . . 6.10.7 Null directive 6.10.8 Predefined macro names . 6.10.9 Pragma operator 6.11 Future language directions 6.11.1 Floating types 6.11.2 Linkages of identifiers . . 6.11.3 External names 6.11.4 Character escape sequences 6.11.5 Storage-class specifiers 6.11.6 Function declarators 6.11.7 Function definitions . . . 6.11.8 Pragma directives 6.11.9 Predefined macro names . 7. Library . . . . . . . . . . . . . . . . . . . . . 7.1 Introduction 7.1.1 Definitions of terms . . . . . . . . . . 7.1.2 Standard headers . . . . . . . . . . . 7.1.3 Reserved identifiers . . . . . . . . . . 7.1.4 Use of library functions 7.2 Diagnostics 7.2.1 Program diagnostics 7.3 Complex arithmetic 7.3.1 Introduction . . . . . . . . . . . . . 7.3.2 Conventions . . . . . . . . . . . . . 7.3.3 Branch cuts . . . . . . . . . . . . . 7.3.4 The CX_LIMITED_RANGE pragma 7.3.5 Trigonometric functions . . . . . . . . 7.3.6 Hyperbolic functions 7.3.7 Exponential and logarithmic functions 7.3.8 Power and absolute-value functions 7.3.9 Manipulation functions 7.4 Character handling . . . . . . . . 7.4.1 Character classification functions 7.4.2 Character case mapping functions 7.5 Errors 7.6 Floating-point environment 7.6.1 The FENV_ACCESS pragma 7.6.2 Floating-point exceptions 7.6.3 Rounding . . . . . . . . . . . . . . 7.6.4 Environment 7.7 Characteristics of floating types . . . 7.8 Format conversion of integer types 7.8.1 Macros for format specifiers 7.8.2 Functions for greatest-width integer types 7.9 Alternative spellings . . . . . . . . . . . 7.10 Sizes of integer types 7.11 Localization . . . . . . . . . . . . . . 7.11.1 Locale control . . . . . . . . . . . . . . . . 7.11.2 Numeric formatting convention inquiry . . . . . . 7.12 Mathematics . . . . . . . . . . . . . . . 7.12.1 Treatment of error conditions . . . . . . . . . . 7.12.2 The FP_CONTRACT pragma 7.12.3 Classification macros 7.12.4 Trigonometric functions . . . . . . . . . . . . 7.12.5 Hyperbolic functions 7.12.6 Exponential and logarithmic functions 7.12.7 Power and absolute-value functions 7.12.8 Error and gamma functions . . . . . . . . . . . 7.12.9 Nearest integer functions . . . . . . . . . . . . Remainder functions Manipulation functions Maximum, minimum, and positive difference functions Floating multiply-add . . . . . . . . . . . . . Comparison macros . . . . . . . . . . . . . . 7.13 Nonlocal jumps 7.13.1 Save calling environment 7.13.2 Restore calling environment 7.14 Signal handling . . . . . . . . . . . . . 7.14.1 Specify signal handling 7.14.2 Send signal . . . . . . . . . . . . . . . . . 7.15 Variable arguments 7.15.1 Variable argument list access macros . . . . . . . 7.16 Boolean type and values 7.17 Common definitions . . . . . . . . . . . 7.18 Integer types . . . . . . . . . . . . . . 7.18.1 Integer types 7.18.2 Limits of specified-width integer types 7.18.3 Limits of other integer types 7.18.4 Macros for integer constants 7.19 Input/output 7.19.1 Introduction . . . . . . . . . . . . . . . . . 7.19.2 Streams 7.19.3 Files . . . . . . . . . . . . . . . . . . . . 7.19.4 Operations on files 7.19.5 File access functions 7.19.6 Formatted input/output functions 7.19.7 Character input/output functions . . . . . . . . . 7.19.8 Direct input/output functions 7.19.9 File positioning functions Error-handling functions . . . . . . . . . . . . . 7.20 General utilities 7.20.1 Numeric conversion functions . . . . . . . . . . . 7.20.2 Pseudo-random sequence generation functions 7.20.3 Memory management functions . . . . . . . . . . 7.20.4 Communication with the environment 7.20.5 Searching and sorting utilities . . . . . . . . . . . 7.20.6 Integer arithmetic functions 7.20.7 Multibyte/wide character conversion functions 7.20.8 Multibyte/wide string conversion functions 7.21 String handling . . . . . . . . . . . . . . 7.21.1 String function conventions . . . . . . . . . . . . 7.21.2 Copying functions 7.21.3 Concatenation functions . . . . . . . . . . . . . 7.21.4 Comparison functions . . . . . . . . . . . . . . 7.21.5 Search functions 7.21.6 Miscellaneous functions . . . . . . . . . . . . . 7.22 Type-generic math 7.23 Date and time 7.23.1 Components of time 7.23.2 Time manipulation functions 7.23.3 Time conversion functions 7.24 Extended multibyte and wide character utilities . . 7.24.1 Introduction . . . . . . . . . . . . . . . . . . 7.24.2 Formatted wide character input/output functions 7.24.3 Wide character input/output functions 7.24.4 General wide string utilities 7.24.5 Wide character time conversion functions 7.24.6 Extended multibyte/wide character conversion utilities . 7.25 Wide character classification and mapping utilities 7.25.1 Introduction . . . . . . . . . . . . . . . . . . 7.25.2 Wide character classification utilities . . . . . . . . 7.25.3 Wide character case mapping utilities . . . . . . . . 7.26 Future library directions 7.26.1 Complex arithmetic . . . . . . . . 7.26.2 Character handling 7.26.3 Errors 7.26.4 Format conversion of integer types 7.26.5 Localization 7.26.6 Signal handling 7.26.7 Boolean type and values 7.26.8 Integer types 7.26.9 Input/output vii General utilities String handling Extended multibyte and wide character utilities Wide character classification and mapping utilities . . . . . . . . . . . . . . Annex A (informative) Language syntax summary A.1 Lexical grammar A.2 Phrase structure grammar . . . . . . . . . A.3 Preprocessing directives Annex B (informative) Library summary B.1 Diagnostics B.2 Complex . . . . . . . . . . . . . . . . B.3 Character handling . . . . . . . . . . . . . B.4 Errors B.5 Floating-point environment B.6 Characteristics of floating types . . . . . . . . B.7 Format conversion of integer types . . . . . B.8 Alternative spellings . . . . . . . . . . . . B.9 Sizes of integer types B.10 Localization . . . . . . . . . . . . . . . B.11 Mathematics . . . . . . . . . . . . . . . . B.12 Nonlocal jumps B.13 Signal handling . . . . . . . . . . . . . . B.14 Variable arguments B.15 Boolean type and values B.16 Common definitions . . . . . . . . . . . . B.17 Integer types . . . . . . . . . . . . . . . B.18 Input/output B.19 General utilities B.20 String handling . . . . . . . . . . . . . . B.21 Type-generic math B.22 Date and time B.23 Extended multibyte/wide character utilities B.24 Wide character classification and mapping utilities . . . . . . . . . . . . . . . . . 437 Annex D (normative) Universal character names for identifiers Annex E (informative) Implementation limits . . . . . . . 438 . . . . . . . . . . . . . . 440 Annex F (normative) IEC 60559 floating-point arithmetic F.1 Introduction F.2 Types . . . . . . . . . . . . . . . . . F.3 Operators and functions viii Annex C (informative) Sequence points F.4 F.5 F.6 F.7 F.8 F.9 Floating to integer conversion Binary-decimal conversion Contracted expressions . . Floating-point environment Optimization . . . . . . Mathematics . Annex G (informative) IEC 60559-compatible complex arithmetic G.1 Introduction G.2 Types . . . . . . . . . . . . . . . . . . . . . G.3 Conventions G.4 Conversions G.5 Binary operators G.6 Complex arithmetic G.7 Type-generic math Annex H (informative) Language independent arithmetic H.1 Introduction H.2 Types . . . . . . . . . . . . . . . . . H.3 Notification Annex I (informative) Common warnings . . . . . . . . . . . . . . . . 485 Annex J (informative) Portability issues . J.1 Unspecified behavior . . . . . J.2 Undefined behavior J.3 Implementation-defined behavior J.4 Locale-specific behavior J.5 Common extensions Bibliography Index . . . . . . . . . . . . . . . . . . . . . . . . . . . 514 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517 ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are member of ISO or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75% of the national bodies casting a vote. International Standard ISO/IEC 9899 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 22, Programming languages, their environments and system software interfaces. The Working Group responsible for this standard (WG 14) maintains a site on the World Wide Web at http:// containing additional information relevant to this standard such as a Rationale for many of the decisions made during its preparation and a log of Defect Reports and Responses. This second edition cancels and replaces the first edition, ISO/IEC 9899:1990, as amended and corrected by ISO/IEC 9899/COR1:1994, ISO/IEC 9899/AMD1:1995, and ISO/IEC 9899/COR2:1996. Major changes from the previous edition include: — restricted character set support via digraphs and (originally specified in AMD1) — wide character library support in and (originally specified in AMD1) — more precise aliasing rules via effective type — restricted pointers — variable-length arrays — flexible array members — static and type qualifiers in parameter array declarators — complex (and imaginary) support in — type-generic math macros in — the long long int type and library functions — increased minimum translation limits — additional floating-point characteristics in — remove implicit int — reliable integer division — universal character names (\u and \U) — extended identifiers — hexadecimal floating-point constants and %a and %A printf/scanf conversion specifiers — compound literals — designated initializers — // comments — extended integer types and library functions in and — remove implicit function declaration — preprocessor arithmetic done in intmax_t/uintmax_t — mixed declarations and code — new block scopes for selection and iteration statements — integer constant type rules — integer promotion rules — macros with a variable number of arguments — the vscanf family of functions in and — additional math library functions in — floating-point environment access in — IEC 60559 (also known as IEC 559 or IEEE arithmetic) support — trailing comma allowed in enum declaration — %lf conversion specifier allowed in printf — inline functions — the snprintf family of functions in — boolean type in — idempotent type qualifiers — empty macro arguments xii