std::reverse

Defined in header <algorithm>

template<class BidirIt > void reverse( BidirIt first, BidirIt last );

Reverses the order of the elements in the range

[first, last)

Behaves as if applying std::iter_swap to every pair of iterators

first+i, (last-i) - 1

for each non-negative

i < (last-first)/2

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::iter_swap(first++, last); } }

Example

Run this code

#include <vector>
#include <iostream>
#include <algorithm>
 
int main()
{
    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';
}      

注意reverse的第二個參數不是序列的最後一個元素的位置，而是此位置之後再向後一個，

Reverses the order of the elements in the range

[first, last)

例子中，reverse  反轉長度4的int數組，第二參數是&a[4](最後一個元素a[3]的後一個)