Library: Algorithms
Function
An algorithm that reverses the order of elements in a sequence
#include <algorithm>
namespace std {
template <class BidirectionalIterator>
void reverse(BidirectionalIterator start,
BidirectionalIterator finish);
}
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 <= (finish - start)/2, reverse() applies iter_swap() to all pairs of iterators start + I, (finish - I) - 1.
reverse() performs exactly (finish - start)/2 swaps.
//
// reverse.cpp
//
#include <algorithm> // for reverse, reverse_copy
#include <vector> // for vector
#include <iostream> // for cout, endl
#include <iterator> // for ostream_iterator
int main ()
{
typedef std::vector<int, std::allocator<int> > Vector;
typedef std::ostream_iterator<int, char,
std::char_traits<char> >
Iter;
// Initialize a vector with an array of integers.
const Vector::value_type a[] = { 1, 2, 3, 4, 5,
6, 7, 8, 9, 10 };
Vector v (a + 0, a + sizeof a / sizeof *a);
// Print out elements in original (sorted) order.
std::cout << "Elements before reverse: \n ";
std::copy (v.begin (), v.end (), Iter (std::cout, " "));
// Reverse the ordering.
std::reverse (v.begin (), v.end ());
// Print out the reversed elements.
std::cout << "\n\nElements after reverse: \n ";
std::copy (v.begin (), v.end (), Iter (std::cout, " "));
std::cout << "\n\nA reverse_copy to cout: \n ";
std::reverse_copy (v.begin (), v.end (),
Iter (std::cout, " "));
std::cout << std::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
ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.9