Algorithm
Reverses the order of elements in a collection.
None
#include <algorithm>
template <class BidirectionalIterator>
void reverse (BidirectionalIterator first,
BidirectionalIterator last);
The algorithm reverse reverses the elements in a sequence so that the last element becomes the new first element, and the first element becomes the new last. For each non-negative integer i <= (last - first)/2, reverse applies swap to all pairs of iterators first + I, (last - I) - 1.
Because the iterators are assumed to be bidirectional, reverse does not return anything.
reverse performs exactly (last - first)/2 swaps.
//
// reverse.cpp
//
#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
int main()
{
//Initialize a vector with an array of ints
int arr[10] = {1,2,3,4,5,6,7,8,9,10};
vector<int> v(arr, arr+10);
//Print out elements in original (sorted) order
cout << "Elements before reverse: " << endl << " ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//Reverse the ordering
reverse(v.begin(), v.end());
//Print out the reversed elements
cout << "Elements after reverse: " << endl << " ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl;
return 0;
}
Program Output
Elements before reverse:
1 2 3 4 5 6 7 8 9 10
Elements after reverse:
10 9 8 7 6 5 4 3 2 1
A reverse_copy to cout:
1 2 3 4 5 6 7 8 9 10
If your compiler does not support default template parameters, then you always need to supply the Allocator template argument. For instance, you need to write:
vector<int, allocator<int> >
instead of:
vector<int>
If your compiler does not support namespaces, then you do not need the using declaration for std.