C17 (C Standard Revision) - Wikipedia

C programming language standard, 2017 revision Not to be confused with C++17.

C language revisions
K&R C ANSI C C99 C11 C17 C23 C2Y
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C17, formally ISO/IEC 9899:2018,[1] is an open standard for the C programming language, prepared in 2017 and published on 5 July 2018.[1] It replaced C11 (standard ISO/IEC 9899:2011),[2] and is superseded by C23 (ISO/IEC 9899:2024) since October 2024.[3] Since it was under development in 2017, and officially published in 2018, C17 is sometimes referred to as C18.[4]

Changes from C11

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C17 fixes numerous minor defects in C11 without introducing new language features.[2]

The __STDC_VERSION__ macro is increased to the value 201710L.

For a detailed list of changes from the previous standard, see Clarification Request Summary for C11. Examples of changes include fixes for #elif, realloc, and typos, among others.[5]

Compiler support

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List of compilers supporting C17:

• GCC 8.1.0[6]
• LLVM Clang 7.0.0[7]
• IAR EWARM v8.40.1[8]
• Microsoft Visual C++ VS 2019 (16.8)[9]
• Pelles C 9.00[10]

See also

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C++ language revisions
C++98 C++03 C++11 C++14 C++17 C++20 C++23 C++26
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• Compatibility of C and C++
• Outline of the C programming language

References

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1. ^ a b "ISO/IEC 9899:2018 - Information technology -- Programming languages -- C". International Organization for Standardization. Archived from the original on 1 April 2025. Retrieved 16 April 2025.
2. ^ a b "The Standard - C". www.iso-9899.info.
3. ^ "WG 14 Document log". www.open-std.org.
4. ^ "Using the GNU Compiler Collection (GCC): C Dialect Options". gcc.gnu.org.
5. ^ ISO/IEC JTC1/SC22/WG14 (October 2017). "Clarification Request Summary for C11 Version 1.13". www.open-std.org. Retrieved 28 September 2020.{{cite web}}: CS1 maint: numeric names: authors list (link)
6. ^ "Using the GNU Compiler Collection (GCC): C Dialect Options". gcc.gnu.org.
7. ^ "Clang 7 documentation — Clang Compiler User's Manual".
8. ^ "IAR Information Center for Arm - Release notes". netstorage.iar.com.
9. ^ "C11 and C17 Standard Support Arriving in MSVC". devblogs.microsoft.com. 14 September 2020.
10. ^ "Changelog - Added support for new C17 standard". www.smorgasbordet.com/pellesc/.

Further reading

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• N2176 (final draft of C17 standard); WG14; 2017-10-09.
• N2310 (post-C17, very early draft of what would become C23; WG14; 2018-11-11.
• ISO/IEC 9899:2018 (official C17 standard); ISO; 2018.

External links

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• C Language WG14 (Working Group 14)

• C Language Working Group 14 (WG14) Documents
• C Language WG14 page, as it appeared on 2018-07-22, just after the publication of C17

Preceded byC11

C language standards

Succeeded byC23

v t e C programming language
ANSI C C99 C11 C17 C23 C2Y Embedded C MISRA C
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