INCITS/ISO/IEC 9899-2011[2012] (ISO/IEC 9899-2011, IDT) Information technology — Programming languages — C INCITS/ISO/IEC 9899-2011[2012] PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. Adopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard. Date of ANSI Approval: 5/23/2012 25 West 43rd Street, New York, New York 10036 (ITI). . These materials are subject to Electrotechnical Commission (IEC), American National Standards Institute (ANSI), and Information Technology Industry Council (ITI). Not for resale. No part of this publication may be reproduced in any form, including an electronic retrieval system, without the prior written permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1250 Eye Street NW, Washington, DC 20005. © ITIC 2012 – Foreword Introduction 1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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 6.2.8 Alignment of objects 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 iii 6.5 Expressions 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 Alignment specifier . . . . 6.7.6 Declarators 6.7.7 Type names . . . . . . . 6.7.8 Type definitions 6.7.9 Initialization Static assertions 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 Power and absolute-value functions 7.3.8 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 Alignment 7.16 Variable arguments 7.16.1 Variable argument list access macros . . . . . . . 7.17 Atomics . . . . . . . . . . . . . . 7.17.1 Introduction . . . . . . . . . . . . . . . . . 7.17.2 Initialization . . . . . . . . . . . . . . . . 7.17.3 Order and consistency . . . . . . . . . . . . . 7.17.4 Fences . . . . . . . . . . . . . . . . . . . 7.17.5 Lock-free property 7.17.6 Atomic integer types 7.17.7 Operations on atomic types . . . . . . . . . . . 7.17.8 Atomic flag type and operations . . . . . . . . . 7.18 Boolean type and values 7.19 Common definitions . . . . . . . . . . . 7.20 Integer types . . . . . . . . . . . . . . 7.20.1 Integer types 7.20.2 Limits of specified-width integer types 7.20.3 Limits of other integer types 7.20.4 Macros for integer constants 7.21 Input/output 7.21.1 Introduction . . . . . . . . . . . . . . 7.21.2 Streams 7.21.3 Files . . . . . . . . . . . . . . . . . 7.21.4 Operations on files 7.21.5 File access functions 7.21.6 Formatted input/output functions 7.21.7 Character input/output functions . . . . . . 7.21.8 Direct input/output functions 7.21.9 File positioning functions Error-handling functions . . . . . . . . . 7.22 General utilities 7.22.1 Numeric conversion functions . . . . . . . 7.22.2 Pseudo-random sequence generation functions 7.22.3 Memory management functions . . . . . . 7.22.4 Communication with the environment 7.22.5 Searching and sorting utilities . . . . . . . 7.22.6 Integer arithmetic functions 7.22.7 Multibyte/wide character conversion functions 7.22.8 Multibyte/wide string conversion functions 7.23 _Noreturn 7.24 String handling . . . . . . . . . . 7.24.1 String function conventions . . . . . . . . 7.24.2 Copying functions 7.24.3 Concatenation functions . . . . . . . . . 7.24.4 Comparison functions . . . . . . . . . . 7.24.5 Search functions 7.24.6 Miscellaneous functions . . . . . . . . . 7.25 Type-generic math 7.26 Threads 7.26.1 Introduction . . . . . . . . . . . . . . 7.26.2 Initialization functions . . . . . . . . . . 7.26.3 Condition variable functions 7.26.4 Mutex functions 7.26.5 Thread functions . . . . . . . . . . . . 7.26.6 Thread-specific storage functions 7.27 Date and time 7.27.1 Components of time 7.27.2 Time manipulation functions 7.27.3 Time conversion functions vii 7.28 Unicode utilities . . . . . . . . . . . . . . 7.28.1 Restartable multibyte/wide character conversion functions 7.29 Extended multibyte and wide character utilities . . 7.29.1 Introduction . . . . . . . . . . . . . . . . . . 7.29.2 Formatted wide character input/output functions 7.29.3 Wide character input/output functions 7.29.4 General wide string utilities 7.29.4.1 Wide string numeric conversion functions 7.29.4.2 Wide string copying functions . . . . . . . 7.29.4.3 Wide string concatenation functions 7.29.4.4 Wide string comparison functions 7.29.4.5 Wide string search functions 7.29.4.6 Miscellaneous functions 7.29.5 Wide character time conversion functions 7.29.6 Extended multibyte/wide character conversion utilities . 7.29.6.1 Single-byte/wide character conversion functions 7.29.6.2 Conversion state functions 7.29.6.3 Restartable multibyte/wide character conversion 7.29.6.4 Restartable multibyte/wide string conversion 7.30 Wide character classification and mapping utilities 7.30.1 Introduction . . . . . . . . . . . . . . . . . . 7.30.2 Wide character classification utilities . . . . . . . . 7.30.2.1 Wide character classification functions 7.30.2.2 Extensible wide character classification 7.30.3 Wide character case mapping utilities . . . . . . . . 7.30.3.1 Wide character case mapping functions 7.30.3.2 Extensible wide character case mapping 7.31 Future library directions . . . . . . . . . . . . . . . . 7.31.1 Complex arithmetic . . . . . . . . 7.31.2 Character handling 7.31.3 Errors 7.31.4 Floating-point environment . . . . . . . 7.31.5 Format conversion of integer types 7.31.6 Localization 7.31.7 Signal handling 7.31.8 Atomics 7.31.9 Boolean type and values Integer types Input/output General utilities viii . . . 442 . . . 451 . . . 453 . . . 453 String handling Date and time Threads . . . . . . . . . . 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 . . . . . . 457 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 Alignment B.15 Variable arguments B.16 Atomics . . . . . . . . . . . . . . . B.17 Boolean type and values B.18 Common definitions . . . . . . . . . . . . B.19 Integer types . . . . . . . . . . . . . . . B.20 Input/output B.21 General utilities B.22 _Noreturn B.23 String handling . . . . . . . . . . . . . . B.24 Type-generic math B.25 Threads . . . . . . . . . . . . . . . . B.26 Date and time B.27 Unicode utilities . . . . . . . . . . . . . . B.28 Extended multibyte/wide character utilities B.29 Wide character classification and mapping utilities Annex C (informative) Sequence points . . . . . . . . . . . . . . . . . 503 Annex D (normative) Universal character names for identifiers . . . . . . . 504 D.1 Ranges of characters allowed . . . . . . . . . . . . . . . . . 504 D.2 Ranges of characters disallowed initially . . . . . . . . . . . . . 504 Annex E (informative) Implementation limits . . . . . . . . . . . . . . 505 Annex F (normative) IEC 60559 floating-point arithmetic . . . . . . F.1 Introduction . . . . . . . . . . . . . . . . . . . . F.2 Types . . . . . . . . . . . . . . . . . . . . . . . F.3 Operators and functions F.4 Floating to integer conversion F.5 Binary-decimal conversion F.6 The return statement . . . . . . . . . . . . . . . . F.7 Contracted expressions . . . . . . . . . . . . . . . . F.8 Floating-point environment F.9 Optimization . . . . . . . . . . . . . . . . . . . . F.10 Mathematics . . . . . . . . . . . . . . . F.10.1 Trigonometric functions . . . . . . . . . . . . F.10.2 Hyperbolic functions F.10.3 Exponential and logarithmic functions F.10.4 Power and absolute value functions F.10.5 Error and gamma functions . . . . . . . . . . . F.10.6 Nearest integer functions . . . . . . . . . . . . F.10.7 Remainder functions F.10.8 Manipulation functions F.10.9 Maximum, minimum, and positive difference functions F.10.10 Floating multiply-add . . . . . . . . . . . . . F.10.11 Comparison macros . . . . . . . . . . . . . . Annex G (normative) IEC 60559-compatible complex arithmetic G.1 Introduction G.2 Types . . . . . . . . . . . . . . . . . . . . G.3 Conventions G.4 Conversions G.4.1 Imaginary types G.4.2 Real and imaginary . . . . . . . . . . . G.4.3 Imaginary and complex G.5 Binary operators G.5.1 Multiplicative operators G.5.2 Additive operators G.6 Complex arithmetic G.6.1 Trigonometric functions . . . . . . . . . G.6.2 Hyperbolic functions G.6.3 Exponential and logarithmic functions G.6.4 Power and absolute-value functions G.7 Type-generic math