C++26

C++26 is the informal name for the version of the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC) 14882 standard for the C++ programming language that follows C++23. The current working draft of this version is N5008.

Features

Changes that have been accepted into C++26 include:

Language

• Unevaluated strings.
• Adding @, $, and ` to the basic character set.
• constexpr cast from void*.
• User-generated static_assert messages.
• Placeholder variables with no name.
• Pack indexing.
• Attributes for structured bindings.
• Erroneous behavior for uninitialized reads.
• = delete("reason");
• Variadic friends.
• constexpr placement new.
• Structured binding declaration as a condition.
• Ordering of constraints involving fold expressions.
• Deleting a pointer to an incomplete type should be ill-formed.
• Structured bindings can introduce a pack.
• Allowing exception throwing in constant-evaluation.
• constexpr structured bindings and references to constexpr variables.
• Oxford variadic comma, i.e. "Deprecate ellipsis parameters without a preceding comma. The syntax (int...) is incompatible with C, detrimental to C++, and easily replaceable with (int, ...)."
• Removing deprecated array comparisons.
• Contracts

Library

• Hashing support for std::chrono value classes
• std::is_within_lifetime
• Native handles in file streams
• Interfacing string streams with std::string_view
• Interfacing std::bitset with std::string_view
• More constexpr for <cmath> and <complex>
• Adding the new 2022 SI prefixes on ratios: std::quecto, std::ronto, std::ronna, and std::quetta
• std::copyable_function
• std::submdspan()
• <contracts>: Design-by-contract support
• <debugging>: Debugging support and language features to aid debugger programs
• <hazard_pointer>: Hazard pointers for threading
• <hive>: Hive data structure support which reuses erased elements' memory
• <inplace_vector>: In-place vector data structure support, which is a resizable, fixed capacity, inplace contiguous array
• <linalg>: A free function linear algebra interface based on the BLAS
• <meta>: Compile-time reflection support
• <rcu>: Support for safe reclamation read-copy-update mechanism
• <simd>: Data-parallel access (Single instruction, multiple data or SIMD) support
• <text_encoding>: Support for accessing the IANA Character Sets registry
• Support for annotations to be used in reflection which behave differently from the existing attribute system used by the compiler
• Added tuple protocol to std::complex
• views::concat
• Concatenation of strings and string views
• std::ranges::generate_random
• Printing blank lines with std::println()
• std::formatter<std::filesystem::path>
• Saturation arithmetic with, among others, std::add_sat, std::div_sat

External links

• Compiler support for C++26 features