std::reverse

`<algorithm>`
	(1)
`template< class BidirIt > void reverse( BidirIt first, BidirIt last );`			(C++20)
`template< class BidirIt > constexpr void reverse( BidirIt first, BidirIt last );`			(C++20)
`template< class ExecutionPolicy, class BidirIt > void reverse( ExecutionPolicy&& policy, BidirIt first, BidirIt last );`		(2)	(C++17)

1) [first, last)

i < (last-first)/2 first+i, (last-i) - 1 std::iter_swap

2) (1) policy std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> true

first, last	-
policy	-

- `BidirIt` ValueSwappable LegacyBidirectionalIterator

()

ExecutionPolicy

ExecutionPolicy std::terminate ExecutionPolicy
std::bad_alloc

libstdc++ libc++

template<class BidirIt>
void reverse(BidirIt first, BidirIt last)
{
    while ((first != last) && (first != --last)) {
        std::iter_swap(first++, last);
    }
}

(last - first)/2

Run this code

#include <vector>
#include <iostream>
#include <iterator>
#include <algorithm>
 
int main()
{
    std::vector<int> v{1,2,3};
    std::reverse(std::begin(v), std::end(v));
    for(auto e : v) std::cout << e;
    std::cout << '\n';
    
    int a[] = {4, 5, 6, 7};
    std::reverse(std::begin(a), std::end(a));
    for(auto e : a) std::cout << e;
}

:

321
7654

reverse_copy

() [edit]






(C++20)





(C++20)




(C++17)
(C++11)
(C++11)
(C++11)

cppreference.com

std::reverse