std::vector::swap

 

C++

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

 

Containers library

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

 

std::vector

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

 

void swap( vector& other );		(until C++17)
void swap( vector& other ) noexcept(/* see below */);		(since C++17)

Exchanges the contents of the container with those of other. Does not invoke any move, copy, or swap operations on individual elements.

All iterators and references remain valid. The past-the-end iterator is invalidated.

If std::allocator_traits<allocator_type>::propagate_on_container_swap::value is true, then the allocators are exchanged using an unqualified call to non-member swap. Otherwise, they are not swapped (and if get_allocator() != other.get_allocator(), the behavior is undefined).

(since C++11)

Parameters

other

-

container to exchange the contents with

Return value

(none)

Exceptions

(none)	(until C++17)
noexcept specification:   noexcept(std::allocator_traits<Allocator>::propagate_on_container_swap::value || std::allocator_traits<Allocator>::is_always_equal::value)	(since C++17)

Complexity

Constant.

See also

std::swap(std::vector)

specializes the std::swap algorithm (function template)

Example

Run this code

#include <vector>
#include <iostream>
 
void printVector(std::vector<int>& vec)
{
    for (int a : vec)
    {
        std::cout << a << " ";
    }
}
 
int main()
{
    std::vector<int> v1{1, 2, 3};
    std::vector<int> v2{7, 8, 9};
 
    std::cout << "v1: ";
    printVector(v1);
 
    std::cout << "\nv2: ";
    printVector(v2);
 
    std::cout << "\n-- SWAP\n";
    v2.swap(v1);
 
    std::cout << "v1: ";
    printVector(v1);
 
    std::cout << "\nv2: ";
    printVector(v2);
}

Output:

v1: 1 2 3
v2: 7 8 9
-- SWAP
v1: 7 8 9
v2: 1 2 3