Template argument deduction for class templates
[*this]{ std::cout << could << " be " << useful << '\n'; }
[[fallthrough]]
, [[nodiscard]]
, [[maybe_unused]]
attributes
using
in attributes to avoid having to repeat an attribute namespace.
Compilers are now required to ignore non-standard attributes they don't recognize.
Simple static_assert(expression);
with no string
no throw
unless throw()
, and throw()
is noexcept(true)
.
std::tie
with auto
const auto [it, inserted] = map.insert( {"foo", bar} );
it
and inserted
with deduced type from the pair
that map::insert
returns.std::array
s and relatively flat structsif (init; condition)
and switch (init; condition)
if (const auto [it, inserted] = map.insert( {"foo", bar} ); inserted)
if(decl)
to cases where decl
isn't convertible-to-bool sensibly.Generalizing range-based for loops
Fixed order-of-evaluation for (some) expressions with some modifications
.then
on future work.Forward progress guarantees (FPG) (also, FPGs for parallel algorithms)
u8'U', u8'T', u8'F', u8'8'
character literals (string already existed)
inherited constructors fixes to some corner cases (see P0136R0 for examples of behavior changes)
std::string
like reference-to-character-array or substringstring const&
again. Also can make parsing a bajillion times faster."hello world"sv
char_traits
std::byte
off more than they could chew.
std::invoke
std::apply
std::make_from_tuple
, std::apply
applied to object construction
is_invocable
, is_invocable_r
, invoke_result
result_of
is_invocable<Foo(Args...), R>
is "can you call Foo
with Args...
and get something compatible with R
", where R=void
is default.invoke_result<Foo, Args...>
is std::result_of_t<Foo(Args...)>
but apparently less confusing?[class.directory_iterator]
and [class.recursive_directory_iterator]
fstream
s can be opened with path
s, as well as with const path::value_type*
strings.
for_each_n
reduce
transform_reduce
exclusive_scan
inclusive_scan
transform_exclusive_scan
transform_inclusive_scan
Added for threading purposes, exposed even if you aren't using them threaded
atomic<T>
::is_always_lockfree
std::lock
pain when locking more than one mutex at a time.std
algorithms, and related machinery[func.searchers]
and [alg.search]
std::function
for allocatorsstd::sample
, sampling from a range?
try_emplace
and insert_or_assign
Splicing for map<>
, unordered_map<>
, set<>
, and unordered_set<>
non-const .data()
for string.
non-member std::size
, std::empty
, std::data
std::begin
/end
The emplace
family of functions now returns a reference to the created object.
unique_ptr<T[]>
fixes and other unique_ptr
tweaks.weak_from_this
and some fixed to shared from thisstd
datatype improvements:{}
construction of std::tuple
and other improvementsC++17 library is based on C11 instead of C99
Reserved std[0-9]+
for future standard libraries
std
implementations exposedstd::clamp()
std::clamp( a, b, c ) == std::max( b, std::min( a, c ) )
roughlygcd
and lcm
std::uncaught_exceptions
std::as_const
std::bool_constant
_v
template variablesstd::void_t<T>
std::owner_less<void>
std::less<void>
, but for smart pointers to sort based on contentsstd::chrono
polishstd::conjunction
, std::disjunction
, std::negation
exposedstd::not_fn
std
std::less
.<codecvt>
memory_order_consume
result_of
, replaced with invoke_result
shared_ptr::unique
, it isn't very threadsafeIsocpp.org has has an independent list of changes since C++14; it has been partly pillaged.
Naturally TS work continues in parallel, so there are some TS that are not-quite-ripe that will have to wait for the next iteration. The target for the next iteration is C++20 as previously planned, not C++19 as some rumors implied. C++1O has been avoided.
Initial list taken from this reddit post and this reddit post, with links added via googling or from the above isocpp.org page.
Additional entries pillaged from SD-6 feature-test list.
clang's feature list and library feature list are next to be pillaged. This doesn't seem to be reliable, as it is C++1z, not C++17.
these slides had some features missing elsewhere.
While "what was removed" was not asked, here is a short list of a few things ((mostly?) previous deprecated) that are removed in C++17 from C++:
register
, keyword reserved for future usebool b; ++b;
<functional>
stuff, random_shuffle
std::function
There were rewordings. I am unsure if these have any impact on code, or if they are just cleanups in the standard:
P0505R0 (constexpr chrono)
P0418R2 (atomic tweaks)
P0512R0 (template argument deduction tweaks)
P0490R0 (structured binding tweaks)
P0513R0 (changes to std::hash
)
P0502R0 (parallel exceptions)
P0509R1 (updating restrictions on exception handling)
P0012R1 (make exception specifications be part of the type system)
P0510R0 (restrictions on variants)
P0504R0 (tags for optional/variant/any)
P0497R0 (shared ptr tweaks)
P0508R0 (structured bindings node handles)
P0521R0 (shared pointer use count and unique changes?)
https://isocpp.org/files/papers/p0636r0.html