History of C

 

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Atomic operations (C11)

Thread support (C11)

Technical Specifications

 

C language

Basic concepts

Keywords

Preprocessor

Statements

Expressions

Initialization

Declarations

Functions

Miscellaneous

History of C

Technical Specifications

 

Early C

• 1969: B created, based on BCPL, to replace PDP-7 assembler as the system programming language for Unix

• added operators ++, --, compound assignment, remained a typeless language like BCPL

• 1971: NB ("new B") created when porting B to PDP-11

• types (int, char, arrays and pointers), array-to-pointer conversion, compilation to machine code

• 1972: Language renamed to C

• structs, operators && and ||, preprocessor, portable I/O

• 1973: Unix re-written in C

• unsigned, long, unions, enumerations, increased type safety

• 1978: The C Programming Language, 1st edition

Standard C

• 1983: ANSI established X3J11 committee
• 1988: The C Programming Language, 2nd edition
• 1989: C89, the ANSI C standard published

1. codified existing practices
2. new features: volatile, enum, signed, void, locales
3. From C++: const, function prototypes

• 1990: C90, the ANSI C standard accepted as ISO/IEC 9899-1990
• 1995: C95 (ISO/IEC 9899 AM1) (online store)

1. greatly expanded wide and multibyte character support (wctype.h, wchar.h, additions and changes to stream I/O, etc)
2. digraphs, iso646.h,

• 1995: Technical corrigendum 1 (ISO/IEC 9899 TCOR1)

• 44 small changes

• 1996: Technical corrigendum 2 (ISO/IEC 9899 TCOR2)

• 24 small changes

• 1999: C99 (ISO/IEC 9899:1999)

1. new features: bool, long long, stdint.h, inttypes.h, restrict, compound literals, variable length arrays, flexible array members, designated initializers, fenv.h, variadic macros, complex numbers, __func__, hexadecimal floating point format (%a), monetary formatting in lconv, isblank, concatenation of narrow and wide string literals, trailing comma in enumerations, empty arguments in function-like macros, STDC_* pragmas, va_copy, null return of tmpnam, null pointer in setvbuf, hh and ll lengthspecifiers in printf, snprintf, _Exit, tgmath.h, POSIX-like strftime specifiers
2. from C++: inline, mix declarations and code, declarations in the init clause of the for loop, // comments, universal character names in source code
3. removed implicit functions and implicit int

• 2001: Technical corrigendum 1 (ISO/IEC 9899:1999/Cor.1:2001(E))

• 11 defects fixed

• 2004: Technical corrigendum 2 (ISO/IEC 9899:1999/Cor.2:2004(E))
• 2004: Unicode TR (ISO/IEC TR 19769:2004) (ISO store) (November 7, 2003 draft)
• 2007: Technical corrigendum 3 (ISO/IEC 9899:1999/Cor.3:2007(E)) (September 7, 2007 draft)

• deprecated gets

• 2007: Bounds-checking interfaces TR (ISO/IEC TR 24731-1:2007) (ISO store) (March 28, 2007 draft)
• 2008: Embedded TR (ISO/IEC TR 18037:2008) (ISO store) (September 24, 2003 draft)
• 2009: Decimal floating-point TR (ISO/IEC TR 24732:2009) (ISO store) (July 5, 2007 draft)
• 2009: Mathematical special functions TR (ISO/IEC TR 24747:2009) (ISO store) (August 2, 2006 draft)
• 2010: Dynamic allocations functions TR (ISO/IEC TR 24731-2:2010) (ISO store) (August 15, 2007 draft)
• 2011: C11 (ISO/IEC 9899:2011) (ISO store) (ANSI store) (April 12, 2011 draft)

1. thread-aware memory model, stdatomic.h, threads.h, type-generic functions, alignas/alignof, noreturn, static assert, analyzability extensions, extensions to complex and imaginary types, anonymous structures and unions, exclusive file open mode. quick_exit
2. removed gets
3. from Bounds-checking interfaces TR: bounds-checking interfaces,
4. from Unicode TR: char16_t, char32_t, and uchar.h

• 2012: Technical corrigendum 1 (ISO/IEC 9899:2011/Cor 1:2012) (ISO store)

• Fixes DR 411

• 2013: Secure Coding Rules TS (ISO/IEC TS 17961:2013) (ISO store) (June 26, 2012)
• 2014: FP TS part 1: Binary floating-point arithmetic (ISO/IEC TS 18661-1:2014) (ISO store) (2013 draft )

1. provides changes to C11 (mostly to Annex F) that cover all basic requirements and some recommendations of IEC 60559:2011 (C11 was built on IEC 60559:1989)

• 2015: FP TS part 2: Decimal floating-point arithmetic (ISO/IEC TS 18661-2:2015) (ISO store) (2015 draft)

1. provides changes to C11 to support all the requirements, plus some basic recommendations, of IEC 60559:2011 for decimal floating-point arithmetic. This supersedes ISO/IEC TR 24732:2009.

• 2015: FP TS part 3: Interchange and extended types (ISO/IEC TS 18661-3:2015) (ISO store) (2015 draft)

1. provides changes to C11 to support the recommendations of IEC 60559:2011 for extended floating‐point formats and the interchange formats, both arithmetic and non-arithmetic.

• 2015: FP TS part 4: Supplementary functions (ISO/IEC TS 18661-4:2015) (ISO store) (2015 draft)

1. provides changes to C11 to support all mathematical operations recommended by IEC 60559:2011, including trigonometry in π units, inverse square root, compounded interest, etc.

• 2016: FP TS part 5: Supplementary attributes (ISO/IEC TS 18661-5:2016) (ISO store)(2016 draft)

1. provides changes to C11 to support all supplementary attributes (evaluation model, exception handling, reproducibility, etc) recommended by IEC 60559:2011

• 2018: C17 (ISO/IEC 9899:2018) (ISO Store) (Final draft)

Includes the deprecation of ATOMIC_VAR_INIT and the fixes to the following defect reports:

Future development

• Parallelism TS (Draft n2017 2016-03-10)
• Transactional Memory TS (Draft n1961 2015-09-23)
• C2x (Draft n2347 2019-03-13)) Next major C language standard revision

• List of issues that were not granted DR status: n2297 (2018-09-24)
• List of post-C11 defect reports (including those scheduled for C2x) n2316 (October 2018)

References

• The Development of the C Language by Dennis M. Ritchie
• Rationale for the C99 standard