< cpp‎ | algorithm
Algorithm library
Execution policies (C++17)
Non-modifying sequence operations
Modifying sequence operations
Operations on uninitialized storage
Partitioning operations
Sorting operations
Binary search operations
Set operations (on sorted ranges)
Heap operations
Minimum/maximum operations
Numeric operations
C library
Defined in header <algorithm>
template< class ForwardIt1, class ForwardIt2 >
ForwardIt2 swap_ranges( ForwardIt1 first1, ForwardIt1 last1, ForwardIt2 first2 );
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2 >
ForwardIt2 swap_ranges( ExecutionPolicy&& policy, ForwardIt1 first1, ForwardIt1 last1, ForwardIt2 first2 );
(2) (since C++17)
1) Exchanges elements between range [first1, last1) and another range starting at first2.
2) Same as (1), but executed according to policy. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true


[edit] Parameters

first1, last1 - the first range of elements to swap
first2 - beginning of the second range of elements to swap
policy - the execution policy to use. See execution policy for details.
Type requirements
ForwardIt1, ForwardIt2 must meet the requirements of ForwardIterator.
The types of dereferenced ForwardIt1 and ForwardIt2 must meet the requirements of Swappable

[edit] Return value

Iterator to the element past the last element exchanged in the range beginning with first2.

[edit] Exceptions

The overload with a template parameter named ExecutionPolicy reports errors as follows:

  • If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the three standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
  • If the algorithm fails to allocate memory, std::bad_alloc is thrown.

[edit] Possible implementation

template<class ForwardIt1, class ForwardIt2>
ForwardIt2 swap_ranges(ForwardIt1 first1, 
                             ForwardIt1 last1, 
                             ForwardIt2 first2)
    while (first1 != last1) {
        std::iter_swap(first1++, first2++);
    return first2;

[edit] Example

Demonstrates swapping of subranges from different containers

#include <algorithm>
#include <list>
#include <vector>
#include <iostream>
int main()
    std::vector<int> v = {1, 2, 3, 4, 5};
    std::list<int> l = {-1, -2, -3, -4, -5};
    std::swap_ranges(v.begin(), v.begin()+3, l.begin());
    for(int n : v)
       std::cout << n << ' ';
    std::cout << '\n';
    for(int n : l)
       std::cout << n << ' ';
    std::cout << '\n';


-1 -2 -3 4 5
1 2 3 -4 -5

[edit] Complexity

linear in the distance between first1 and last1

[edit] See also

swaps the elements pointed to by two iterators
(function template) [edit]
swaps the values of two objects
(function template) [edit]