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std::reverse

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< cpp‎ | algorithm
Revision as of 06:19, 14 November 2012 by Rauy (Talk | contribs)

 
 
 

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Defined in header <algorithm>
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template< class BidirIt >
void reverse( BidirIt first, BidirIt last );
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Reverses the order of the elements in the range [first, last).

Contents

Parameters

first, last - the range of elements to reverse
Type requirements
-
BidirIt must meet the requirements of BidirectionalIterator.
-
The type of dereferenced BidirIt must meet the requirements of Swappable.

Return value

(none)

Possible implementation

template<class BidirIt>
void reverse(BidirIt first, BidirIt 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

Template:cpp/algorithm/dcl list reverse copy