Editing C (programming language) (section)

=== Early developments ===
{| class="wikitable floatright" style="margin-left: 1.5em;"
|+Timeline of C language
|-
! Year
! Informal<br />name
! Official<br />standard
|-
| 1972
| first release
| {{N/A}}
|-
| 1978
| [[K&R C]]
| {{N/A}}
|-
| 1989,<br />1990
| [[ANSI C]], C89,<br />ISO C, C90
| ANSI X3.159-1989<br />ISO/IEC 9899:1990
|-
| 1999
| [[C99]], C9X
| ISO/IEC 9899:1999
|-
| 2011
| [[C11 (C standard revision)|C11]], C1X
| ISO/IEC 9899:2011
|-
| 2018
| [[C17 (C standard revision)|C17]], C18
| ISO/IEC 9899:2018
|-
| 2024
| [[C23 (C standard revision)|C23]], C2X
| ISO/IEC 9899:2024
|-
| {{TBA}}
| [[#C2Y|C2Y]]
|
|}

The origin of C is closely tied to the development of the [[Unix]] operating system, originally implemented in [[assembly language]] on a [[PDP-7]] by [[Dennis Ritchie]] and [[Ken Thompson]], incorporating several ideas from colleagues.  Eventually, they decided to port the operating system to a [[PDP-11]]. The original PDP-11 version of Unix was also developed in assembly language.<ref name="sigplan" />

==== B ====
{{main|B (programming language)}}
Thompson wanted a programming language for developing utilities for the new platform. He first tried writing a [[Fortran]] compiler, but he soon gave up the idea and instead created a cut-down version of the recently developed [[systems programming language]] called [[BCPL]]. The official description of BCPL was not available at the time,<ref name="NFDsZ">{{cite web |url=https://www.lysator.liu.se/c/dmr-on-histories.html |first=Dennis |last=Ritchie |title=BCPL to B to C |website=lysator.liu.se |access-date=September 10, 2019 |archive-date=December 12, 2019 |archive-url=https://web.archive.org/web/20191212221532/http://www.lysator.liu.se/c/dmr-on-histories.html |url-status=live }}</ref> and Thompson modified the syntax to be less 'wordy' and similar to a simplified [[ALGOL]] known as SMALGOL.<ref name="Ars">{{Cite web |last=Jensen |first=Richard |date=December 9, 2020 |title="A damn stupid thing to do"—the origins of C |url=https://arstechnica.com/features/2020/12/a-damn-stupid-thing-to-do-the-origins-of-c/ |access-date=March 28, 2022 |website=Ars Technica |language=en-us |archive-date=March 28, 2022 |archive-url=https://web.archive.org/web/20220328143845/https://arstechnica.com/features/2020/12/a-damn-stupid-thing-to-do-the-origins-of-c/ |url-status=live }}</ref> He called the result [[B (programming language)|''B'']],<ref name="sigplan" /> describing it as "BCPL semantics with a lot of SMALGOL syntax".<ref name=Ars /> Like BCPL, B had a [[bootstrapping]] compiler to facilitate porting to new machines.<ref name=Ars /> Ultimately, few utilities were written in B because it was too slow and could not take advantage of PDP-11 features such as [[byte]] addressability.

==== New B and first C release ====
In 1971 Ritchie  started to improve B, to use the features of the more-powerful PDP-11.  A significant addition was a character data type.  He called this ''New B'' (NB).<ref name=Ars />  Thompson started to use NB to write the [[Research Unix|Unix]] kernel, and his requirements shaped the direction of the language development.<ref name="Ars" /><ref name="unixport" />  Through to 1972, richer types were added to the NB language: NB had arrays of <code>int</code> and <code>char</code>. Pointers, the ability to generate pointers to other types, arrays of all types, and types to be returned from functions were all also added. Arrays within expressions became pointers. A new compiler was written, and the language was renamed C.<ref name=sigplan />

The C compiler and some utilities made with it were included in [[Version 2 Unix]], which is also known as [[Research Unix]].<ref name="QtqTh">{{cite tech report |first=M. D. |last=McIlroy |author-link=Doug McIlroy |year=1987 |url=http://www.cs.dartmouth.edu/~doug/reader.pdf |title=A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 |series=CSTR |number=139 |institution=Bell Labs |format=PDF |page=10 |access-date=February 1, 2015 |archive-date=November 11, 2017 |archive-url=https://web.archive.org/web/20171111151817/http://www.cs.dartmouth.edu/~doug/reader.pdf |url-status=live }}</ref>

==== Structures and Unix kernel re-write ====
At [[Version 4 Unix]], released in November 1973, the [[Unix]] [[kernel (operating system)|kernel]] was extensively re-implemented in C.<ref name="sigplan" /> By this time, the C language had acquired some powerful features such as <code>struct</code> types.

The [[C preprocessor|preprocessor]] was introduced around 1973 at the urging of [[Alan Snyder (computer scientist)|Alan Snyder]] and also in recognition of the usefulness of the file-inclusion mechanisms available in BCPL and [[PL/I]]. Its original version provided only included files and simple string replacements: <code>#include</code> and <code>#define</code> of parameterless macros. Soon after that, it was extended, mostly by [[Mike Lesk]] and then by John Reiser, to incorporate macros with arguments and [[conditional compilation]].<ref name="sigplan">{{harvtxt|Ritchie|1993}}</ref>

Unix was one of the first operating system kernels implemented in a language other than [[assembly language|assembly]]. Earlier instances include the [[Multics]] system (which was written in [[PL/I]]) and [[Master Control Program]] (MCP) for the [[Burroughs large systems|Burroughs B5000]] (which was written in [[ALGOL]]) in 1961. In around <!--Better?: {{Circa|1977}}--> 1977, Ritchie and [[Stephen C. Johnson]] made further changes to the language to facilitate [[Software portability|portability]] of the Unix operating system.  Johnson's [[Portable C Compiler]] served as the basis for several implementations of C on new platforms.<ref name="unixport">{{cite journal |last1=Johnson |first1=S. C. |author-link1=Stephen C. Johnson |last2=Ritchie |first2=D. M. |author-link2=Dennis Ritchie |title=Portability of C Programs and the UNIX System |journal=Bell System Tech. J. |year=1978 |volume=57 |issue=6 |pages=2021–2048 |doi=10.1002/j.1538-7305.1978.tb02141.x |citeseerx=10.1.1.138.35 |s2cid=17510065 |issn = 0005-8580 }} (Note: The PDF is an OCR scan of the original, and contains a rendering of "IBM 370" as "IBM 310".)</ref>