std::vector<T,Allocator>::swap (3) - Linux Manuals

std::vector<T,Allocator>::swap: std::vector<T,Allocator>::swap

NAME

std::vector<T,Allocator>::swap - std::vector<T,Allocator>::swap

Synopsis

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 (since C++17)
|| std::allocator_traits<Allocator>::is_always_equal::value)

Complexity

Constant.

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