std::reverse

 

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Defined in header <algorithm>
template< class BidirectionalIterator > void reverse( BidirectionalIterator first, BidirectionalIterator last );

Reverses the order of the elements in the range [first, last).

Parameters

first, last

-

the range of elements to reverse

Return value

(none)

Possible implementation

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

Example

#include <vector>
#include <iostream>
#include <algorithm>
 
int main(int argc, char** argv)
{
    std::vector<int> v({1,2,3});
    std::reverse(std::begin(v), std::end(v));
    std::cout << v[0] << v[1] << v[2] << '\n';
 
    int a[] = {4, 5, 6, 7};
    std::reverse(&a[0], &a[4]);
    std::cout << a[0] << a[1] << a[2] << a[3] << '\n';
}

Output:

321
7654

Complexity

linear in the distance between first and last

See also

reverse_copy	creates a copy of a range that is reversed (function template)