From cppreference.com
Defined in header
template<classForwardIt1,classForwardIt2>ForwardIt2swap_ranges(ForwardIt1first1,ForwardIt1last1,ForwardIt2first2); (1)(constexpr since C++20)template<classExecutionPolicy,classForwardIt1,classForwardIt2>ForwardIt2swap_ranges(ExecutionPolicy&&policy,ForwardIt1first1,ForwardIt1last1,ForwardIt2first2); (2) (since C++17)1) Exchanges elements between the two ranges [first1, last1) and [first2, std::next(first2,std::distance(first1,next1))).
2) Same as (1), but executed according to policy.
This overload participates in overload resolution only if the value of the following expression is true:
std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>
(until C++20)std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>
(since C++20)If any of the following conditions is satisfied, the behavior is undefined:
The two ranges overlap.
There exists a pair of corresponding iterators iter1 and iter2 in the two ranges such that *iter1 is not
with *iter2.
Parameters
first1, last1 - the pair of iterators defining the first
first2 - beginning of the second range policy - the
to use Type requirements -ForwardIt1, ForwardIt2 must meet the requirements of
. Return value
The past-the-end iterator of the second range.
Complexity
Exactly std::distance(first1,last1) swaps.
Exceptions
2) During the execution process:
If the temporary memory resources required for parallelization are not available,
is thrown.
If an uncaught exception is thrown while accessing objects via an algorithm argument, the behavior is determined by the execution policy (for
,
is invoked).
Notes
Implementations (e.g.
) may enable vectorization when the iterator type satisfies
and swapping its value type calls neither non-trivial special member function nor
-found swap.
Possible implementation
template<classForwardIt1,classForwardIt2>constexpr//< since C++20ForwardIt2swap_ranges(ForwardIt1first1,ForwardIt1last1,ForwardIt2first2){for(;first1!=last1;++first1,++first2)std::iter_swap(first1,first2);returnfirst2;}Example
Demonstrates swapping of subranges from different containers.
Run this code
#include<algorithm>#include<iostream>#include<list>#include<vector>autoprint=[](autocomment,constauto&seq){std::cout<<comment;for(constauto&e:seq)std::cout<<e<<' ';std::cout<<'\n';};intmain(){std::vector<char>v{'a','b','c','d','e'};std::list<char>l{'1','2','3','4','5'};print("Before swap_ranges:\n""v: ",v);print("l: ",l);std::swap_ranges(v.begin(),v.begin()+3,l.begin());print("After swap_ranges:\n""v: ",v);print("l: ",l);}Output:
Before swap_ranges: v: a b c d e l: 1 2 3 4 5 After swap_ranges: v: 1 2 3 d e l: a b c 4 5 See also