std:: reverse_copy

Parameters

Return value

Output iterator to the element past the last element copied.

Complexity

Exactly \(\scriptsize N\) N assignments.

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 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.

Possible implementation

See also the implementations in libstdc++ , libc++ , and MSVC STL .

template<class BidirIt, class OutputIt>
constexpr // since C++20
OutputIt reverse_copy(BidirIt first, BidirIt last, OutputIt d_first)
{
    for (; first != last; ++d_first)
        *d_first = *(--last);
    return d_first;
}

Notes

Implementations (e.g. MSVC STL ) may enable vectorization when the both iterator types satisfy LegacyContiguousIterator and have the same value type, and the value type is TriviallyCopyable .

Example

#include <algorithm>
#include <iostream>
#include <vector>
 
int main()
{
    auto print = [](const std::vector<int>& v)
    {
        for (const auto& value : v)
            std::cout << value << ' ';
        std::cout << '\n';
    };
 
    std::vector<int> v{1, 2, 3};
    print(v);
 
    std::vector<int> destination(3);
    std::reverse_copy(std::begin(v), std::end(v), std::begin(destination));
    print(destination);
 
    std::reverse_copy(std::rbegin(v), std::rend(v), std::begin(destination));
    print(destination);
}

1 2 3 
3 2 1 
1 2 3

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

1. ↑ ^{1.0 1.1 1.2} LegacyOutputIterator is not required to support binary + and - . The usages of + and - here are exposition-only: the actual computation does not need to use them.

See also