atomic operations library
emplace() and other use of rvalue references throughout all parts of the existing library
- std::unique_ptr
- std::move_iterator
std::initializer_list
stateful and scoped allocators
std::forward_list
chrono library
ratio library
new algorithms
Unicode conversion facets
thread library
std::exception_ptr
std::error_code and std::error_condition
iterator improvements:
- std::begin
- std::end
- std::next
- std::prev
Unicode conversion functions

C++14(2014)

Language features

variable templates
generic lambdas
lambda captures expressions
new/delete elision
relaxed restrictions on constexpr functions
binary literals
digit separators
return type deduction for functions
aggregate classes with default non-static member initializers.

Library features

std::make_unique:
std::shared_timed_mutex and std::shared_lock
std::integer_sequence
std::exchange
std::quoted
and many small improvements to existing library facilities such as
- two-range overloads for some algorithms
- type alias versions of type traits
- user-defined string
- duration
- and complex number literals
- etc.

C++17(2017)

Obsolete:

Removed

auto_ptr
deprecated function objects
std::random_shuffle
std::unexpected
the obsolete iostreams aliases
trigraphs
the register keyword
bool increment

Deprecated

std::iterator
std::raw_storage_iterator
std::get_temporary_buffer
std::is_literal_type
std::result_of
all of <codecvt>

Language features:

fold-expressions
class template argument deduction
auto non-type template parameters
compile-time if constexpr
inline variables
structured bindings
initializers for if and switch
u8-char
simplified nested namespaces
using-declaration can declare multiple names
made noexcept part of type system
new order of evaluation rules
guaranteed copy elision
lambda capture of *this
constexpr lambda
attribute namespaces don’t have to repeat
new attributes [[fallthrough]] [[nodiscard]] and [[maybe_unused]]
__has_include

Headers:

<any>
<optional>
<variant>
<memory_resource>
<string_view>
<charconv>
<execution>
<filesystem>

Library features:

In utility

tuple:
- apply
- deduction_guides
- make_from_tuple
variant
launder
to_chars/from_chars
as_const
searchers
optional
any
not_fn

In memory

uninitialized memory tools
- destroy_at
- destroy
- destroy_n
- uninitialized_move
- uninitialized_value_construct
weak_from_this
polymorphic allocators
aligned_alloc
transparent owner_less
array support for shared_ptr
allocation functions with explicit alignment
variadic lock_guard
cache line interface

In types

byte
conjunction/disjunction/negation
type trait variables xxx_v
is_swappable
is_invocable
is_aggregate
has_unique_object_representations.

In algorithm

clamp
execution policies
reduce
inclusive_scan
exclusive_scan

container related

map/set extract and map/set merge
map/unordered_map try_emplace and insert_or_assign
contiguous iterators
non-member size/empty/data

In numeric

mathematical special functions
gcd
lcm
3D hypot

Other

is_always_lock_free
uncaught_exceptions
timespec_get
rounding functions for duration and time_point

C++20(2020)

Language features

Feature test macros
3-way comparison operator <=> and operator==() = default
designated initializers
init-statements and initializers in range-for
char8_t
[[no_unique_address]]
[[likely]]
[[unlikely]]
pack-expansions in lambda captures
removed the requirement to use typename to disambiguate types in many contexts
consteval, constinit
further relaxed constexpr
signed integers are 2’s complement
aggregate initialization using parentheses
Coroutines
Modules
Constraints and concepts
Abbreviated function templates
DR: array new can deduce array size

Library features

Headers

<concepts>
<coroutine>
<compare>
<version>
<source_location>
<format>
<span>
<ranges>
<bit>
<numbers>
<syncstream>
in Thread support library:
<stop_token>
<semaphore>
<latch>
<barrier>

Library features

Formatting library
Calendar and Time Zone library
std::source_location
std::span
std::endian
array support for std::make_shared
std::remove_cvref
std::to_address
floating point and shared_ptr atomics
std::barrier, std::latch, and std::counting_semaphore
std::jthread and thread cancellation classes
<version>
std::osyncstream
std::u8string and other char8_t uses
constexpr for <algorithm>, <utility>, <complex>
std::string::starts_with / ends_with and * std::string_view::starts_with / ends_with
std::assume_aligned
std::bind_front
std::c8rtomb/std::mbrtoc8
std::make_obj_using_allocator etc
std::make_shared_for_overwrite/std::make_unique_for_overwrite
heterogeneous lookup in unordered associative containers
std::polymoprhic_allocator with additional member functions and * std::byte as its default template argument
std::execution::unseq
std::midpoint and std::lerp
std::ssize
std::is_bounded_array, std::is_unbounded_array
Ranges
uniform container erasure (std::erase/std::erase_if)
Mathematical constants

C++ Evolution

Early C++

C with classes(1979)

C++(1985)

C++2.0(1989 & 1990)

Standard C++

C++98(1998)

C++03(2003)

Modern C++

C++11(2011)

C++14(2014)

C++17(2017)

C++20(2020)

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