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The Standard - C
iso-9899.info › wiki › The_Standard
The Standard - C - this wiki
The international standard which defines the C programming language is ISO/IEC 9899 a joint effort of ISO and IEC and the participating countries via their national body's all of which make the standard available via whatever publishing arrangement(s) each makes, many of which are available ...
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ISO
iso.org › standard › 74528.html
ISO/IEC 9899:2018 - Information technology — Programming languages — C
Information technology — Programming ... · ISO/IEC 9899:2018 · 74528 · Withdrawn (Edition 4, 2018) New version available: ISO/IEC 9899:2024 · 1 This document specifies the form and establishes the interpretation of programs written in the C ...
Discussions

is there any official documentation of C programming
The "official" documentation for the C programming language is the ISO Standard . You can purchase it there, or from another standards organisation (which might be cheaper!). Or you can instead consult one of the freely-available "draft" specifications instead. The latest of these is N3054 . This should include everything that will be in the upcoming C23 standard. More on reddit.com
🌐 r/C_Programming
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January 19, 2023
Where do I find the current C or C++ standard documents? - Stack Overflow
C++11 – Working draft (N3337) as plain text document: (https://port70.net/~nsz/c/c++/c++11_n3337.txt) (The site hosting the plain text version of the C++11 working draft also has some C++14 drafts in this format. But none of them are copies of the final working draft, N4140.) ... Print copies of the standards are available from national standards bodies and ISO ... More on stackoverflow.com
🌐 stackoverflow.com
A C enthusiast's rant about the ISO standard
Of course, being so used to the ... review, and lots of trial and error, I now understand C much better—and enjoy it more, too. But here's my issue: When I went looking for the official ISO standard documentation...... More on reddit.com
🌐 r/C_Programming
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August 1, 2025
c - Where can one find the C89/C90 standards in PDF format? - Stack Overflow
Even in the Stack Overflow questions ... standard documents? and The C Standard, Obtaining the Standard don’t contain what I’m looking for. Web searches didn’t helped either, nor did Open Standards. ... You can find a draft of the C99 Standard at open-std.org/JTC1/sc22/wg14/www/docs/n1256.pdf (or draft C11). I believe the Standard proper cannot be obtained for free. ... You can buy the standard from ISO... More on stackoverflow.com
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Standard C++
isocpp.org › std › the-standard
The Standard : Standard C++
The current ISO C++ standard is C++23, formally known as ISO International Standard ISO/IEC 14882:2024(E) -- Programming Language C++.
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ISO
iso.org › standard › 57853.html
ISO/IEC 9899:2011 - Information technology — Programming languages — C
ISO/IEC 9899:2011 specifies the form and establishes the interpretation of programs written in the C programming language.It specifies
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GNU
gnu.org › software › gnu-c-manual › gnu-c-manual.html
The GNU C Reference Manual
This is a reference manual for the C programming language as implemented by the GNU Compiler Collection (GCC). Specifically, this manual aims to document: The 1989 ANSI C standard, commonly known as “C89” · The 1999 ISO C standard, commonly known as “C99”, to the extent that C99 is ...
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Open-std
open-std.org › jtc1 › sc22 › wg14 › www › docs › n2310.pdf pdf
N2310 ::: diff :::::: marks — November 6, 2018 ISO/IEC 9899:2017:: 2x (E)
1)This document is designed to promote the portability of C programs among a variety of data-processing systems. It is · intended for use by implementors and programmers. Annex J gives an overview of portability issues that a C program might ... ISO/IEC 2382:2015, Information technology — ...
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ANSI
blog.ansi.org › home › the current c programming language standard – iso/iec 9899:2024 (c24)
The Current C Programming Language Standard - ISO/IEC 9899:2024 (C24) - ANSI Blog
June 4, 2025 - ISO/IEC 9899:2024 - Information technology - Programming languages – C (C24) is the current standard that originated as ANSI X3.159-1989.
Find elsewhere
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PDF versions of the standard

As of 1st September 2014 March 2022 September 2025, the best locations by price for the official C and C++ standards documents in PDF seem to be:

  • C++23 – ISO/IEC 14882:2024: 221 CHF (about $277 US) from iso.org or $287 from Accuris

  • C++20 – ISO/IEC 14882:2020: $212 from csagroup.org

  • C++17 – ISO/IEC 14882:2017: $141.75 NZD (about $84 US) from Standards New Zealand

  • C++14 – ISO/IEC 14882:2014: $141.75 NZD (about $84 US) from Standards New Zealand

  • C++11 – ISO/IEC 14882-2011: $50.40 from ansi.org or $60 from Accuris

  • C++03 – INCITS/ISO/IEC 14882:2003: $50.40 from ansi.org. Also available from the British Standards Institute at a higher price (£165 for members, £330 for non-members - about $224 US and $447 US respectively)

  • C++98 – ISO/IEC 14882:1998: $106.31 NZD (about $63 US) from Standards New Zealand

  • C23 – ISO/IEC 9899:2024: 221 CHF (about $277 US) from iso.org. Also available from the BSI (British Standards Institute). £165 for members, £330 for non-members (about $224 US and $447 US respectively)

  • C17 – INCITS/ISO/IEC 9899:2018: $116 from INCITS/ANSI / N2176 / c17_updated_proposed_fdis.pdf draft from November 2017 (Link broken, see Wayback Machine N2176)

  • C11 – ISO/IEC 9899:2011: $60 from ansi.org / WG14 draft version N1570

  • C99 – INCITS/ISO/IEC 9899-1999(R2005): $60 from ansi.org / WG14 draft version N1256

  • C90 – ISO/IEC 9899:1990: $90 NZD (about $65 USD) from Standards New Zealand

Non-PDF electronic versions of the standard

Warning: most copies of standard drafts are published in PDF format, and errors may have been introduced if the text/HTML was transcribed or automatically generated from the PDF.

  • latest C standard – ISO Online Browsing Platform, viewable but not downloadable: (https://www.iso.org/obp/ui/#iso:std:iso-iec:9899)
  • C89 – Draft version in ANSI text format: (https://web.archive.org/web/20161223125339/http://flash-gordon.me.uk/ansi.c.txt)
  • C89 – Draft version as HTML document: (https://port70.net/~nsz/c/c89/c89-draft.html)
  • C90 TC1; ISO/IEC 9899 TCOR1, single-page HTML document: (https://www.open-std.org/jtc1/sc22/wg14/www/docs/tc1.htm)
  • C90 TC2; ISO/IEC 9899 TCOR2, single-page HTML document: (https://www.open-std.org/jtc1/sc22/wg14/www/docs/tc2.htm)
  • C99 – Draft version (N1256) as HTML document: (https://port70.net/~nsz/c/c99/n1256.html)
  • C11 – Draft version (N1570) as HTML document: (https://port70.net/~nsz/c/c11/n1570.html)
  • C++11 – Working draft (N3337) as plain text document: (https://port70.net/~nsz/c/c%2B%2B/c%2B%2B11_n3337.txt)

(The site hosting the plain text version of the C++11 working draft also has some C++14 drafts in this format. But none of them are copies of the final working draft, N4140.)

Print versions of the standard

(Information last checked 13th September 2025.)

Print copies of the standards are available from national standards bodies and ISO but are more expensive than PDF copies.

  • C++23 – ISO/IEC 14882:2024: $287 from Accuris

  • C++20 – ISO/IEC 14882:2020: from the BSI (British Standards Institute). £165 for members, £330 for non-members (about $224 US and $447 US respectively)

  • C++17 – ISO/IEC 14882:2017: $194.63 NZD (about $116 US) from Standards New Zealand

  • C++14 – ISO/IEC 14882:2014: $194.63 NZD (about $116 US) from Standards New Zealand

  • C++11 – ISO/IEC 14882-2011: $60 from Accuris

  • C++03 – ISO/IEC 14882:2003: from the BSI (British Standards Institute). £165 for members, £330 for non-members (about $224 US and $447 US respectively) but copies are available on Amazon for much less

  • C++98 – ISO/IEC 14882:1998: $118.13 NZD (about $70 US) from Standards New Zealand

  • C23 – ISO/IEC 9899:2024: Available from the BSI (British Standards Institute). £165 for members, £330 for non-members (about $224 US and $447 US respectively)

  • C17 – INCITS/ISO/IEC 9899:2018: from the BSI (British Standards Institute). £165 for members, £330 for non-members (about $224 US and $447 US respectively)

  • C11 – ISO/IEC 9899:2011: from the BSI (British Standards Institute). £165 for members, £330 for non-members (about $224 US and $447 US respectively)

Other print versions of the standard

If you want a hard copy of the C90 standard for much less money than above, you may be able to find a cheap used copy of Herb Schildt's book The Annotated ANSI Standard at Amazon, which contains the actual text of the standard (useful) and commentary on the standard (less useful - it contains several dangerous and misleading errors).

A version of the C99 standard incorporating the first technical corrigendum, again from the BSI and published by Wiley, is also available. However, as C99 had three technical corrigenda during its lifetime, and the most commonly-used C99 draft (N1256) incorporates all three, a version with only the first corrigendum may not correspond closely enough to C99 as used by most compilers.

  • C99 Standard (incorporating Technical Corrigendum 1) on Amazon

Standards committee draft versions (free)

The working drafts for future standards are often available from the committee websites:

  • C++ committee website
  • C committee website

If you want to get drafts from the current or earlier C/C++ standards, there are some available for free on the internet:

For C:

  • ANSI X3.159-198 (C89): I cannot find a PDF of C89, but it is almost the same as C90. The only major differences are in the boilerplate and section numbering, although there are some slight textual differences

  • ISO/IEC 9899:1990 (C90): (Almost the same as ANSI X3.159-198 (C89) except for the frontmatter and section numbering. There is at least one textual difference in section 6.5.7 (previously 3.5.7), where "a list" became "a brace-enclosed list". Note that the conversion between ANSI and ISO/IEC Standard is seen inside this document, the document refers to its name as "ANSI/ISO: 9899/99" although this isn't the right name of the later made standard of it, the right name is "ISO/IEC 9899:1990")

  • TC1 for C90: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n423.pdf

  • There isn't a PDF link for TC2 on the WG14 website, sadly.

  • ISO/IEC 9899:1999 (C99 incorporating all three Technical Corrigenda): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

  • An earlier version of C99 incorporating only TC1 and TC2: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf

  • Working draft for the original (i.e. pre-corrigenda) C99: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n843.htm (HTML) and https://web.archive.org/web/20240307022041/http://std.dkuug.dk/JTC1/SC22/WG14/www/docs/n843.pdf (PDF). Note that there were two later working drafts: N869 and N878, but they seem to have been removed from the WG14 website, so this is the latest one available.

  • List of changes between C89/C90 and C99: https://port70.net/~nsz/c/c89/c9x_changes.html

  • TC1 for C99 (only the TC, not the standard incorporating it): https://www.open-std.org/jtc1/sc22/wg14/www/docs/9899tc1/n32071.PDF

  • TC2 for C99 (only the TC, not the standard incorporating it): https://www.open-std.org/jtc1/sc22/wg14/www/docs/9899-1999_cor_2-2004.pdf

  • ISO/IEC 9899:2011 (C11): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf

    For information on the differences between N1570 and the final, published version of C11, see Latest changes in C11 and https://groups.google.com/g/comp.std.c/c/v5hsWOu5vSw

  • ISO/IEC 9899:2011/Cor 1:2012 (C11's only technical corrigendum): This can be viewed at https://www.iso.org/obp/ui/#iso:std:iso-iec:9899:ed-3:v1:cor:1:v1:en but cannot be downloaded. It is the actual corrigendum, not a draft.

  • ISO/IEC 9899:2018 (C17): https://web.archive.org/web/20181230041359if_/http://www.open-std.org/jtc1/sc22/wg14/www/abq/c17_updated_proposed_fdis.pdf (N2176)

  • C23 post-publication - working baseline draft (functionally identical to C23 as-published, including NB comments): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3299.pdf

  • C2y work-in-progress - latest working draft as of April 2025 (N3550): https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3550.pdf

For C++:

  • ISO/IEC 14882:1998 (C++98): https://web.archive.org/web/20221121042402/http://www.lirmm.fr/~ducour/Doc-objets/ISO+IEC+14882-1998.pdf

  • ISO/IEC 14882:2003 (C++03): https://web.archive.org/web/20180922024431/https://cs.nyu.edu/courses/fall11/CSCI-GA.2110-003/documents/c++2003std.pdf

  • ISO/IEC 14882:2011 (C++11): https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf

  • ISO/IEC 14882:2014 (C++14): https://github.com/cplusplus/draft/blob/master/papers/n4140.pdf?raw=true

  • ISO/IEC 14882:2017 (C++17): https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/n4659.pdf

  • ISO/IEC 14882:2020 (C++20): https://isocpp.org/files/papers/N4860.pdf

  • ISO/IEC 14882:2023 (C++23): https://open-std.org/jtc1/sc22/wg21/docs/papers/2023/n4950.pdf

Note that these documents are not the same as the standard, though the versions just prior to the meetings that decide on a standard are usually very close to what is in the final standard. The FCD (Final Committee Draft) versions are password protected; you need to be on the standards committee to get them.

Even though the draft versions might be very close to the final ratified versions of the standards, some of this post's editors would strongly advise you to get a copy of the actual documents — especially if you're planning on quoting them as references. Of course, starving students should go ahead and use the drafts if strapped for cash.


It appears that, if you are willing and able to wait a few months after ratification of a standard, to search for "INCITS/ISO/IEC" instead of "ISO/IEC" when looking for a standard is the key. By doing so, one of this post's editors was able to find the C11 and C++11 standards at reasonable prices. For example, if you search for "INCITS/ISO/IEC 9899:2011" instead of "ISO/IEC 9899:2011" on webstore.ansi.org you will find the reasonably priced PDF version.


The site https://wg21.link/ provides short-URL links to the C++ current working draft and draft standards, and committee papers:

  • https://wg21.link/std11 - C++11
  • https://wg21.link/std14 - C++14
  • https://wg21.link/std17 - C++17
  • https://wg21.link/std20 - C++20
  • https://wg21.link/std23 - C++23
  • https://wg21.link/std - current working draft (as of May 2022 still points to the 2021 version)

The current draft of the standard is maintained as LaTeX sources on Github. These sources can be converted to HTML using cxxdraft-htmlgen. The following sites maintain HTML pages so generated:

  • Tim Song - Current working draft - C++11 - C++14 - C++17 - C++20 - C++23
  • Eelis - Current working draft

Tim Song also maintains generated HTML and PDF versions of the Networking TS and Ranges TS.

POSIX extensions to the C standard

The POSIX standard (IEEE 1003.1) requires a compliant operating system to include a C compiler. This compiler must in turn be compliant with the C standard, and must also support various extensions defined in the "System Interfaces" section of POSIX (such as the off_t data type, the <aio.h> header, the clock_gettime() function and the _POSIX_C_SOURCE macro.)

So if you've tried to look up a particular function, been informed "This function is part of POSIX, not the C standard", and wondered why an operating system standard was mandating compiler features and language extensions... now you know!

  • POSIX.1-2001: The System Interfaces section can be downloaded as a separate document from https://mirror.math.princeton.edu/pub/oldlinux/download/c951.pdf. Section 1.7 states that the relevant version of the C standard is C99.

    The "Shell and Utilities" section (https://mirror.math.princeton.edu/pub/oldlinux/download/c952.pdf) mandates not only that a C99-compliant compiler should exist, but that it should be invokable from the command line under the name "c99". One way in which this can be implemented is to place a shell script called "c99" in /usr/bin, which calls gcc with the -std=c99 option added to the list of command-line parameters, and blocks any competing standards from being specified.

    POSIX.1-2001 had two technical corrigenda, one dated 2002 and one dated 2004. I don't think they're incorporated into the documents as linked above. There's an online HTML version incorporating the corrigenda at https://pubs.opengroup.org/onlinepubs/009695399/ - but I should add that I've had some trouble with the search box and so using Google to search the site is probably your best bet.

    There is a paywalled link to download the first corrigendum at https://standards.ieee.org/standard/1003_1-2001-Cor1-2002.html.

    There is also a paywalled link for the second at https://standards.ieee.org/standard/1003_1-2001-Cor2-2004.html

  • There is a draft version of POSIX.1-2008 at https://www.open-std.org/jtc1/sc22/open/n4217.pdf.

    POSIX.1-2008 also had two technical corrigenda, the latter of the two being dated 2016. There is an online HTML version of the standard incorporating the corrigenda at https://pubs.opengroup.org/onlinepubs/9699919799.2016edition/ - though, again, I have had situations where the site's own search box wasn't good for finding information.

  • There is an online HTML version of POSIX.1-2017 at https://pubs.opengroup.org/onlinepubs/9699919799/ - though, again, I recommend using Google instead of that site's searchbox. According to the Open Group website "IEEE 1003.1-2017 ... is a revision to the 1003.1-2008 standard to rollup the standard including its two technical corrigenda (as-is)". Linux manpages describe it as "technically identical" to POSIX.1-2008 with Technical Corrigenda 1 and 2 applied. This is therefore not a major revision and does not change the value of the _POSIX_C_SOURCE macro.

  • There is an online HTML version of POSIX.1-2024 (currently the latest version of POSIX.1) at https://pubs.opengroup.org/onlinepubs/9799919799/ - though, once again, I still recommend using Google instead of the site's searchbox. The Open Group website referred in 2019 to "a major revision anticipated to be available in 2023", and consistent with this, the _POSIX_C_SOURCE macro has a new value of 202405L to indicate POSIX.1-2024. (source: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap02.html)

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Online versions of the standard can be found:

Working Draft, Standard for Programming Language C++

The following all draft versions of the standard:

All the following are freely downloadable
2026-05-12: N5046 -- -- Editor's Note N5047
2025-12-15: N5032 -- -- Editor's Note N5033
2025-08-05: N5014 -- -- Editor's Note N5015
2025-03-15: N5008 -- -- Editor's Notes N5009
2024-12-17: N5001 -- -- Editor's Notes N5002
2024-10-16: N4993 -- -- Editor's Notes N4994
2024-08-05: N4988 -- -- Editor's Notes N4989
2024-07-16: N4986 -- -- Editor's Notes N4987
2024-04-16: N4981 -- -- Editor's Notes N4982
2023-12-18: N4971 -- -- Editor's Notes N4972
2023-10-15: N4964 -- -- Editor's Notes N4965
2023-08-14: N4958 -- -- Editor's Notes N4959

This is the C++23 Standard:
2023-05-10: N4950 -- -- Editors Notes N4951

As a source for the above, see N4951, which states:
"N4950 is the current and final working draft for C++23. It replaces N4944, and it forms the basis of the Draft International Standard for C++23. ... The next working draft will be for C++26."

The following all draft versions of the standard:
All the following are freely downloadable
2023-03-22: N4944
2022-12-18: N4928 -- -- Editors Notes N4929
2022-09-05: N4917 -- -- Editors Notes N4918
2022-03-17: N4910 -- -- Editors Notes N4911
2021-10-22: N4901 -- -- Editors Notes N4902
2021-06-18: N4892 -- -- Editors Notes N4893
2021-03-17: N4885 -- -- Editors Notes N4886
2020-12-15: N4878 -- -- Editors Notes N4879
2020-10-18: N4868 -- -- Editors Notes N4867
2020-04-08: N4861

This is the C++20 Standard:
2020-04-08: N4860

Note regarding N4860 and N4861:
According to N4859 git:
"The contents of N4860 and N4861 are identical except for the cover sheet, page headers and footers, and except that N4861 does not contain an index of cross references from ISO C++ 2017."

The following all draft versions of the standard:
All the following are freely downloadable
(many of these can be found at this main GitHub link)
2020-01-14: N4849 git n4850
2019-11-27: N4842 git n4843
2019-10-08: N4835 git
2019-08-15: N4830 git
2019-06-17: N4820 git
2019-03-15: N4810 git
2019-01-21: N4800 git
2018-11-26: N4791 git
2018-10-08: N4778 git
2018-07-07: N4762 git
2018-05-07: N4750 git
2018-04-02: N4741 git
2018-02-12: N4727 git
2017-11-27: N4713 git
2017-10-16: N4700 git
2017-07-30: N4687 git

This is the old C++17 Standard:
This version requires authentication:
2017-03-21: N4660
This version does not require authentication:
2017-03-21: N4659 git

N4661 explicitly states that: "The contents of N4659 and N4660 are identical except for the cover sheet and page headings."

The following all draft versions of the standard:
All the following are freely downloadable

2017-02-06: N4640 git
2016-11-28: N4618 git
2016-07-12: N4606 git
2016-05-30: N4594 git
2016-03-19: N4582 git
2015-11-09: N4567 git
2015-05-22: N4527 git
2015-04-10: N4431 git
2014-11-19: N4296 git

This is the old C++14 standard:
These version requires Authentication
2014-10-07: N4140 git Essentially C++14 with minor errors and typos corrected
2014-09-02: N4141 git Standard C++14
2014-03-02: N3937
2014-03-02: N3936 git

The following all draft versions of the standard:
All the following are freely downloadable
2013-10-13: N3797 git
2013-05-16: N3691
2013-05-15: N3690
2012-11-02: N3485
2012-02-28: N3376
2012-01-16: N3337 git Essentially C++11 with minor errors and typos corrected

This is the old C++11 Standard:
This version requires Authentication
2011-04-05: N3291

The following all draft versions of the standard:
All the following are freely downloadable
2011-02-28: N3242 (differences from N3291 very minor)
2010-11-27: N3225
2010-08-21: N3126
2010-03-29: N3090
2010-02-16: N3035
2009-11-09: N3000
2009-09-25: N2960
2009-06-22: N2914
2009-03-23: N2857
2008-10-04: N2798
2008-08-25: N2723
2008-06-27: N2691
2008-05-19: N2606
2008-03-17: N2588
2008-02-04: N2521
2007-10-22: N2461
2007-08-06: N2369
2007-06-25: N2315
2007-05-07: N2284
2006-11-03: N2134
2006-04-21: N2009
2005-10-19: N1905
2005-04-27: N1804

This is the old C++03 Standard:
All the below versions require Authentication
2004-11-05: N1733
2004-07-16: N1655 Unofficial
2004-02-07: N1577 C++03 (Or Very Close)
2001-09-13: N1316 Draft Expanded Technical Corrigendum
1997-00-00: N1117 Draft Expanded Technical Corrigendum

The following all draft versions of the standard:
All the following are freely downloadable
1996-00-00: N0836 Draft Expanded Technical Corrigendum
1995-00-00: N0785 Working Paper for Draft Proposed International Standard for Information Systems - Programming Language C++

Other Interesting Papers:

2026 / 2025 / 2024 / 2023 / 2022 / 2021 / 2020 / 2019 / 2018 / 2017 / 2016 / 2015 / 2014 / 2013 / 2012 / 2011

🌐
GNU
gnu.org › software › libc › manual › html_node › ISO-C.html
ISO C (The GNU C Library)
HTML compressed (gzipped tar file) - with one web page per node. Info document (gzipped tar file).
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Uchile
dii.uchile.cl › ~daespino › files › Iso_C_1999_definition.pdf pdf
ISO/IEC 9899:1999(E) -- Programming Languages -- C
defined in this International Standard are to be interpreted according to ISO 31−11. ... Where only one of these two actions is meant, ‘‘read’’ or ‘‘modify’’ is used. ... Expressions that are not evaluated do not access objects. ... results, to behaving during translation ...
🌐
IBM
ibm.com › docs › en › xl-c-and-cpp-aix › 13.1.0
Standards and specifications - IBM Documentation
March 5, 2021 - Information Technology - Programming languages - C, ISO/IEC 9899:2011, also known as C11.
🌐
GeeksforGeeks
geeksforgeeks.org › c language › c-programming-language-standard
Standard in C - GeeksforGeeks
C99 (ISO/IEC 9899:1999) introduced several new features, including variable-length arrays, flexible array members, complex numbers, inline functions, and designated initializers.
Published   October 15, 2025
🌐
DevDocs
devdocs.io › c
DevDocs — C documentation
C API documentation with instant search, offline support, keyboard shortcuts, mobile version, and more.
🌐
Reddit
reddit.com › r/c_programming › a c enthusiast's rant about the iso standard
r/C_Programming on Reddit: A C enthusiast's rant about the ISO standard
August 1, 2025 - To add to this, typically the "paid-for" version is usually what's used by compiler writers, so they can say that it's actually "ISO compliant". For the person writing the code that wants to understand what the "standard is doing", looking at the compilers documentation itself is usually a better choice as some of the standard is absolutely open to interpretation.
🌐
ISO
iso.org › standard › 68564.html
ISO/IEC 14882:2017 - Programming languages — C++
ISO/IEC 14882:2017 specifies requirements for implementations of the C++ programming language. The first such requirement is that they implement the language, so this document also defines C++. Other requirements and relaxations of the first ...
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GNU
gnu.org › software › gnu-c-manual › gnu-c-manual.pdf pdf
The GNU C Reference Manual Trevis Rothwell James Youngman
Compiler Collection (GCC). Specifically, this manual aims to document: • The 1989 ANSI C standard, commonly known as “C89” · • The 1999 ISO C standard, commonly known as “C99”, to the extent that C99 is
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Open-std
open-std.org › jtc1 › sc22 › wg21 › docs › standards
C++ - Standards
The ISO/IEC 14882:2017 5th edition was published 2017-12. The ISO/IEC 14882:2020 6th edition was published 2020-12. A draft for the 2003 edition with the combined C++ standard from 1998 and the corrigendum is available in N1316. A draft for the 2011 edition is available in N3242.
Top answer
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127

You can find nice HTML versions of C89, C99, and C11, as well as some of the official draft PDF files they're generated from, here:

http://port70.net/~nsz/c/

Some other useful direct links to free PDF files of the C89/C90, C99 and C11 standards are listed below:

C89/C90: https://www.pdf-archive.com/2014/10/02/ansi-iso-9899-1990-1/ansi-iso-9899-1990-1.pdf

C99: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

C11: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf

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There's exactly one remaining place that I know of where you can still purchase an official NON-DRAFT version of the original ANSI C89 standard. This one place is Standards Australia. Their web-store link for C89 is here:

http://www.techstreet.com/standards/as-3955-1991?product_id=1178768

Don't get confused by the fact that it's called 9899:1990, because that's just the ISO number that C89 got when the ISO absorbed it from ANSI in 1990. And also don't be dissuaded by the fact the Australian Standards document number is "AS 3955-1991," because 1991 is probably just the year that they themselves absorbed it from the ISO.

Note the Abstract given on that page:

Copy[Abstract]
Specifies the form and establishes the interpretation of programs written in
the C programming language. This Standard is identical with and has been
reproduced from ISO/IEC 9899:1990.

That document really is the original ANSI C89 standard, just in a re-re-printed form. If you have 160.29 USD to fork over, you can get a copy for digital download of the PDF or the printed edition for the same price.

Once you have the standard, then all amendments and technical corrigenda can be found here, for free:

http://www.open-std.org/jtc1/sc22/wg14/www/standards

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Cppreference
cppreference.com
cppreference.com
C++ reference C++11, C++14, C++17, C++20, C++23, C++26, C++29 │ Compiler support C++11, C++14, C++17, C++20, C++23, C++26, C++29 · Preprocessor − Comments ASCII chart Basic concepts Keywords Names (lookup) Types (fundamental types) The main function Modules (C++20) Contracts (C++26) ...