std::vector::vector
From cppreference.com
| (1) | ||
| explicit vector( const Allocator& alloc = Allocator() ); |
(until C++14) | |
| vector() : vector( Allocator() ) {} explicit vector( const Allocator& alloc ); |
(since C++14) | |
| (2) | ||
| explicit vector( size_type count, const T& value = T(), |
(until C++11) | |
| vector( size_type count, const T& value, |
(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, |
(4) | |
| vector( const vector& other ); |
(5) | |
| vector( const vector& other, const Allocator& alloc ); |
(5) | (since C++11) |
| vector( vector&& other ) |
(6) | (since C++11) |
| vector( vector&& other, const Allocator& alloc ); |
(6) | (since C++11) |
| vector( std::initializer_list<T> init, const Allocator& alloc = Allocator() ); |
(7) | (since C++11) |
Constructs a new container from a variety of data sources, optionally using a user supplied allocator alloc.
1) Default constructor. Constructs an empty container.
2) Constructs the container with
count copies of elements with value value.4) Constructs the container with the contents of the range
[first, last).
This constructor has the same effect as overload (2) if InputIt is an integral type. |
(until C++11) |
This overload only participates in overload resolution if InputIt satisfies InputIterator , to avoid ambiguity with the overload (2). |
(since C++11) |
5) Copy constructor. Constructs the container with the copy of the contents of
other. If alloc is not provided, allocator is obtained by calling std::allocator_traits<allocator_type>::select_on_container_copy_construction(other.get_allocator().6) Move constructor. Constructs the container with the contents of
other using move semantics. If alloc is not provided, allocator is obtained by move-construction from the allocator belonging to other.7) Constructs the container with the contents of the initializer list
init. Contents |
[edit] Parameters
| 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 |
[edit] Complexity
1) Constant
2-3) Linear in
count4) Linear in distance between
first and last5) Linear in size of
other6) Constant. If
alloc is given and alloc != other.get_allocator(), then linear.7) Linear in size of
initNotes
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.
Exceptions1)
noexcept specification:
noexcept(noexcept(Allocator())) 6) noexcept specification:
noexcept |
(since C++17) |
[edit] Example
Run this code
#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]
[edit] See also
| assigns values to the container (public member function) | |
| assigns values to the container (public member function) |