std::vector::vector

	(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(), 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)
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.

3) Constructs the container with count default-inserted instances of T. No copies are made.

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 as if 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.

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 count

4) Linear in distance between first and last

5) Linear in size of other

6) Constant. If alloc is given and alloc != other.get_allocator(), then linear.

7) Linear in size of init

[edit] Notes

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.

Exceptions

1)

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

assign	assigns values to the container (public member function)
operator=	assigns values to the container (public member function)

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications

array (C++11)
vector
deque
forward_list (C++11)
list
set
multiset
map
multimap
unordered_set (C++11)
unordered_multiset (C++11)
unordered_map (C++11)
unordered_multimap (C++11)
stack
queue
priority_queue

Member functions
vector::vector
vector::~vector
vector::operator=
vector::assign
vector::get_allocator
Element access
vector::at
vector::operator[]
vector::front
vector::back
vector::data (C++11)
Iterators
vector::beginvector::cbegin (C++11)
vector::endvector::cend (C++11)
vector::rbeginvector::crbegin (C++11)
vector::rendvector::crend (C++11)
Capacity
vector::empty
vector::size
vector::max_size
vector::reserve
vector::capacity
vector::shrink_to_fit (C++11)
Modifiers
vector::clear
vector::insert
vector::emplace (C++11)
vector::erase
vector::push_back
vector::emplace_back (C++11)
vector::pop_back
vector::resize
vector::swap