C++17

C++17 (also called C++1z) is the informal name for the future revision of the C++ ISO/IEC standard. The specification for the C++17 revision is under development and "nearly feature-complete"^[1] to be finished in 2017.

Expected features

• Addition of a default text message for static_assert^[2]
• Addition of std::string_view, a non-owning reference to a character sequence or string-slice^[3]
• Removal of trigraphs^[4][5]
• Allow typename in a template template parameter^[6]
• New rules for auto deduction from braced-init-list^[7][8]
• std::uncaught_exceptions, as a replacement of std::uncaught_exception^[9][10]
• Nested namespace definition^[8][11]
• Attributes for namespaces and enumerators^[10][12]
• UTF-8 character literals^[10][13]
• Constant evaluation for all non-type template arguments^[10][14]
• Folding expressions^[10][15]
• New insertion functions for std::map and std::unordered_map^[16][17]
• Uniform container access^[17][18]
• Definition of "contiguous iterators"^[17][19]
• Removal of some deprecated types and functions like std::auto_ptr, std::random_shuffle or old function adaptors^[20][8]
• A file system library based on boost::filesystem^[21]
• Parallel versions of STL algorithms^[22]
• Additional mathematical special functions^[23]
• Most of Library Fundamentals TS I (e.g. std::optional, std::any)^[24][25]
• std::variant, a type-safe union container
• A compile-time static if with the form if constexpr(expression)
• Structured bindings, allowing auto [a, b] = getTwoReturnValues();
• Initializers in if and switch statements
• Guaranteed copy elision by compilers in some cases
• Some extensions on aligned memory allocation
• Template deduction of constructors, allowing pair(5.0, false) instead of pair<double,bool>(5.0, false)
• Inline variables, which allows the declaration of variables in header files

Next standard

• C++20^[26]

See also

• C++
• C++11
• C++14

References

1. Recent milestones: C++17 nearly feature-complete, second round of TSes now under development
2. "N3928: Extending static_assert, v2 (Walter E. Brown)" (PDF).
3. "std::basic_string_view - cppreference.com". en.cppreference.com. Retrieved 2016-06-23.
4. "N3981: Removing trigraphs??! (Richard Smith)". 2014-05-06.
5. IBM comment on preparing for a Trigraph-adverse future in C++17, IBM paper N4210, 2014-10-10. Authors: Michael Wong, Hubert Tong, Rajan Bhakta, Derek Inglis
6. "N4051: Allow typename in a template template parameter (Richard Smith)".
7. "N3922: New Rules for auto deduction from braced-init-list (James Dennett)".
8. "Updates to my trip report".
9. "N4259: Wording for std::uncaught_exceptions (Herb Sutter)" (PDF).
10. "New core language papers adopted for C++17".
11. "N4230: Nested namespace definition (Robert Kawulak, Andrew Tomazos)".
12. "N4266: Attributes for namespaces and enumerators (Richard Smith)".
13. "N4267: Adding u8 character literals (Richard Smith)".
14. "N4268: Allow constant evaluation for all non-type template arguments (Richard Smith)".
15. "N4295: Folding expressions (Andrew Sutton, Richard Smith)".
16. "N4279: Improved insertion interface for unique-key maps (Thomas Köppe)".
17. "New standard library papers adopted for C++17".
18. "N4280: Non-member size() and more (Riccardo Marcangelo)" (PDF).
19. "N4284: Contiguous Iterators (Jens Maurer)".
20. "N4190: Removing auto_ptr, random_shuffle(), And Old <functional> Stuff (Stephan T. Lavavej)".
21. "Filesystem Library Proposal (Beman Dawes)".
22. "The Parallelism TS Should be Standardized".
23. "Mathematical Special Functions for C++17, v5" (PDF).
24. "Adopt Library Fundamentals V1 TS Components for C++17 (R1)".
25. "Current Status".
26. https://herbsutter.com/2016/06/30/trip-report-summer-iso-c-standards-meeting-oulu/ "the next standard after C++17 will be C++20"