This document enumerates all the major changes that have been applied to the C++ working draft since the publication of C++11, up to the publication of C++14. Major changes are those that were added in the form of a dedicated paper, although not all papers are mentioned individually. The remaining papers are listed summarily below. Issue resolutions from the CWG or LWG issues lists are generally not included, but the containing papers are part of the summary listing. Defect reports that are not part of the published International Standard are marked with a “DR” superscript.
| Document | Summary | Examples, notes |
|---|---|---|
| N3733 | Remove gets() |
This unsafe I/O function from the C library is no longer available. |
| N3924 | Discourage rand() |
This low-quality random number facility from the C library is discouraged in favour of the <random> library. |
| Document | Summary | Examples, notes |
|---|---|---|
| N3649 | Polymorphic lambdas | Lambda expressions may now define function templates: [](auto x) { return x * 2; } |
| N3648 | Generalized lambda capture | Lambda captures may now be initialized: [a = 10, b = std::move(b)](){} |
| N3651 | Variable templates | template <typename T> constexpr T pi = 4; |
| N3472 | Binary integer literals | int pi = 0b101001100; |
| N3781 | Digit separators | int pi = 1'010'011'000; |
| N3760 | [[deprecated]] attribute |
An attribute to mark deprecated names and entities. |
| N3656 | Creation function make_unique |
std::unique_ptr<Base> p = std::make_unique<Derived>(arg1, arg2, arg3); |
| N3668 | Algorithm exchange |
T exchange(T& x, U&& val) { T tmp = std::move(x); x = std::forward<U>(val); return tmp; } |
| N3657 | Heterogeneous lookup for associative containers | The concept of a “transparent comparator” is introduced, which, if used,
adds function template overloads find/erase etc.
to associative containers. Convenience predicates less<> etc. are provided. |
|
N3659, N3891, LWG 2288 |
A shared mutex | Reader/writer locking provided by class shared_timed_mutex and guard class shared_lock. |
| N3658 | Compile-time integer sequences | integer_sequence, index_sequence, make_index_sequence etc., to allow tag dispatch on integer packs. |
| N3654 | Quoted strings | std::cout << std::quoted(s); |
|
N3642, N3779 |
User-defined literals | for strings and chrono for complex |
| Document | Summary | Examples, notes |
|---|---|---|
| N3638 | Return type deduction for normal functions | auto f() { return 10; } declares int f();. In C++11, return type deduction was only available for lambda expressions. |
| CWG975 | Return type deduction for lambdas |
The return type of a lambda expression can be deduced even if there are multiple return
statements. This makes lambda return type deduction work the same way as ordinary function return
type deduction (see above). This is intended as a defect report against C++11. |
| N3669 | Constexpr member functions without const | A constexpr member function is no longer implicitly const. Only for
data members does constexpr imply const now. |
| N3652 | Relaxing constraints on constexpr functions | constexpr functions are far less restricted. |
| N3653 | Member initializers and aggregates | A class with default member initializers may now be an aggregate: struct X { int a; int b = 10; }; X val = { 5 }; |
| CWG974 | Default arguments for lambdas |
Lambda expressions can now have default arguments: auto f = [](int a = 10){}; f();
This is intended as a defect report against C++11. |
| N3778 | Sized deallocation | Deallocation functions may now be void operator delete(void* ptr, size_t len) |
| N3664 | Mergeable allocation | Adjacent dynamic allocations may now be fused into fewer, larger calls to operator new/operator delete |
| N3624 | CWG1512: Pointer comparison vs qualification conversions | |
| N3667 | CWG1402: Deleted defaulted ctor | |
| CWG1288 | Direct-list-initialization of references |
References can now be initalized correctly using direct-list-initialization: int & r { n };
Previously, list-initialization would have called for a temporary. This is intended as a defect report against C++11. |
| N3922DR | New rules for auto deduction from braced lists |
Previously, auto a{1, 2, 3}, b{1}; was allowed and both
variables were of type initializer_list<int>.
Now auto a{1, 2, 3}; is ill-formed and auto b{1};
declares an int. Note that auto a = {1, 2, 3}, b = {1};
remains unchanged and deduces initializer_list<int>. |
| N3670 | Addressing tuples by type | std::get<int>(my_tuple) = 10; Ill-formed if the type is not unique. |
| N3545 | integral_constant::operator() |
Given integral_constant<int, 123> x;, x() recovers the value 123. |
|
N3302, N3470, N3469, N3471, N3789 |
constexpr changes |
for complexfor containers for chrono for utilities for functional |
| N3671 | 4-iterator sequence operations | Algorithms that operate on two ranges get new overloads that take being and end iterators for both ranges rather than requiring the second range to be sufficiently long. |
| N3655 | Alias templates for traits | template <typename T> using foo_t = foo<T> for traits, e.g. decay_t. Part 4 of the paper is not applied. |
| N3776 | future destructor |
A clarification that the destructor of future does not normally block, except when it does. |
| N3910 | CWG1441: signal handlers | A clarification on atomic operations and synchronization in signal handlers. |
| Document | Summary | Examples, notes |
|---|---|---|
| N3786 | Prohibiting “out of thin air” results | |
| N3927 | Definition of lock-free | |
| N3323 | Contextual conversions | A new notion of “contextual convertibility” |
The following minor papers are not listed above: N3346, N3644. The following papers contain accepted CWG issues: N3330, N3382, N3383, N3539, N3713, N3833, N3914. The following papers contain accepted LWG issues: N3318, N3438, N3673, N3522, N3754, N3788, N3930.