C17 (C standard revision) explained

C17 is the informal name for ISO/IEC 9899:2018,^[1] a standard for the C programming language, prepared in 2017 and published in June 2018. It replaced C11 (standard ISO/IEC 9899:2011),^[2] and will be superseded by C23 (ISO/IEC 9899:2023) when it is published in 2024.^[3] Since it was under development in 2017, and officially published in 2018, C17 is sometimes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

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.^[5]

Compiler support

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

• C++23, C++20, C++17, C++14, C++11, C++03, C++98, versions of the C++ programming language standard
• Compatibility of C and C++

Further reading

• N2176 (final draft of C17 standard); WG14; 2017.
• ISO/IEC 9899:2018 (official C17 standard); ISO; 2018.

External links

• C Language Working Group 14 (WG14) Documents

Notes and References

1. Web site: ISO/IEC 9899:2018 - Information technology -- Programming languages -- C. International Organization for Standardization.
2. Web site: The Standard - C. www.iso-9899.info.
3. Web site: WG 14 Document log. www.open-std.org.
4. Web site: Using the GNU Compiler Collection (GCC): C Dialect Options. gcc.gnu.org.
5. Web site: ISO/IEC JTC1/SC22/WG14 . Clarification Request Summary for C11 Version 1.13 . www.open-std.org . 28 September 2020 . October 2017.
6. Web site: Using the GNU Compiler Collection (GCC): C Dialect Options. gcc.gnu.org.
7. Web site: Clang 7 documentation — Clang Compiler User's Manual.
8. Web site: IAR Information Center for Arm - Release notes. netstorage.iar.com.
9. Web site: C11 and C17 Standard Support Arriving in MSVC. 14 September 2020. devblogs.microsoft.com.
10. Web site: Changelog - Added support for new C17 standard. www.smorgasbordet.com/pellesc/.