(1) | ||
vector(); explicit vector( const Allocator& alloc ); | (until C++17) | |
vector() noexcept(noexcept(Allocator())); explicit vector( const Allocator& alloc ) noexcept; | (since C++17) | |
(2) | ||
explicit vector( size_type count, const T& value = T(), const Allocator& alloc = Allocator()); | (until C++11) | |
vector( size_type count, const T& value, const Allocator& alloc = Allocator()); | (since C++11) | |
(3) | ||
explicit vector( size_type count ); | (since C++11) (until C++14) | |
explicit vector( size_type count, const Allocator& alloc = Allocator() ); | (since C++14) | |
template< class InputIt > vector( InputIt first, InputIt last, const Allocator& alloc = Allocator() ); | (4) | |
vector( const vector& other ); | (5) | |
vector( const vector& other, const Allocator& alloc ); | (5) | (since C++11) |
(6) | ||
vector( vector&& other ); | (since C++11) (until C++17) | |
vector( vector&& other ) noexcept; | (since C++17) | |
vector( vector&& other, const Allocator& alloc ); | (7) | (since C++11) |
vector( std::initializer_list<T> init, const Allocator& alloc = Allocator() ); | (8) | (since C++11) |
Constructs a new container from a variety of data sources, optionally using a user supplied allocator alloc
.
count
copies of elements with value value
.[first, last)
. This constructor has the same effect as vector(static_cast<size_type>(first), static_cast<value_type>(last), a) if InputIt is an integral type. | (until C++11) |
This overload only participates in overload resolution if InputIt satisfies LegacyInputIterator, to avoid ambiguity with the overload (2). | (since C++11) |
other
. If alloc
is not provided, allocator is obtained as if by calling std::allocator_traits<allocator_type>::select_on_container_copy_construction(other.get_allocator())
.other
using move semantics. Allocator is obtained by move-construction from the allocator belonging to other
. After the move, other
is guaranteed to be empty()
.alloc
as the allocator for the new container, moving the contents from other
; if alloc != other.get_allocator()
, this results in an element-wise move. (in that case, other
is not guaranteed to be empty after the move)init
. alloc | - | allocator to use for all memory allocations of this container |
count | - | the size of the container |
value | - | the value to initialize elements of the container with |
first, last | - | the range to copy the elements from |
other | - | another container to be used as source to initialize the elements of the container with |
init | - | initializer list to initialize the elements of the container with |
count
first
and last
other
alloc != other.get_allocator()
, otherwise constant.init
.Calls to Allocator::allocate
may throw.
After container move construction (overload (6)), references, pointers, and iterators (other than the end iterator) to other
remain valid, but refer to elements that are now in *this
. The current standard makes this guarantee via the blanket statement in §23.2.1[container.requirements.general]/12, and a more direct guarantee is under consideration via LWG 2321.
The overload (3) zeroes out elements of non-class types such as int
, which is different from the behavior of new[]
, which leaves them uninitialized. To match the behavior of new[]
, a custom Allocator::construct can be provided which leaves such elements uninitialized.
#include <vector> #include <string> #include <iostream> template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<T>& v) { s.put('['); char comma[3] = {'\0', ' ', '\0'}; for (const auto& e : v) { s << comma << e; comma[0] = ','; } return s << ']'; } int main() { // c++11 initializer list syntax: std::vector<std::string> words1 {"the", "frogurt", "is", "also", "cursed"}; std::cout << "words1: " << words1 << '\n'; // words2 == words1 std::vector<std::string> words2(words1.begin(), words1.end()); std::cout << "words2: " << words2 << '\n'; // words3 == words1 std::vector<std::string> words3(words1); std::cout << "words3: " << words3 << '\n'; // words4 is {"Mo", "Mo", "Mo", "Mo", "Mo"} std::vector<std::string> words4(5, "Mo"); std::cout << "words4: " << words4 << '\n'; }
Output:
words1: [the, frogurt, is, also, cursed] words2: [the, frogurt, is, also, cursed] words3: [the, frogurt, is, also, cursed] words4: [Mo, Mo, Mo, Mo, Mo]
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2193 | C++11 | the default constructor is explicit | made non-explicit |
assigns values to the container (public member function) |
|
assigns values to the container (public member function) |
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