swap_ranges()

Library:  Algorithms

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Algorithm that exchanges a range of values in one location with those in another

#include <algorithm>

namespace std {
  template <class ForwardIterator1, class ForwardIterator2>
  ForwardIterator2 
  swap_ranges(ForwardIterator1 start1,
              ForwardIterator1 finish1,
              ForwardIterator2 start2);
}

The swap_ranges() algorithm exchanges corresponding values in two ranges, in the following manner:

For each non-negative integer n < (finish - start), the function exchanges *(start1 + n) with *(start2 + n)). After completing all exchanges, swap_ranges() returns an iterator that points to the end of the second container (in other words, start2 + (finish1 -start1)). The result of swap_ranges() is undefined if the two ranges [start, finish) and [start2, start2 + (finish1 - start1)) overlap.

//
//  swap.cpp
//

#include <algorithm>   // for copy, iter_swap
#include <iostream>    // for cout, endl
#include <iterator>    // for ostream_iterator
#include <vector>      // for vector

int main ()
{
    typedef std::ostream_iterator<int, char, 
                                  std::char_traits<char> > Iter;

    const int a[] = { 6, 7, 8, 9, 10, 1, 2, 3, 4, 5 };

    // Set up a vector
    std::vector<int, std::allocator<int> > 
                   v (a, a + sizeof a / sizeof *a);

    // Output original vector.
    std::cout << "For the vector: ";
    std::copy (v.begin (), v.end (), Iter (std::cout, " "));

    // Swap the first five elements with the last five elements
    std::swap_ranges (v.begin (), v.begin () + 5, 
                      v.begin () + 5);

    // Output result
    std::cout << "\n\nSwapping the first five elements "
              << "with the last five gives: \n     ";

    std::copy (v.begin (), v.end (), Iter (std::cout," "));

    // Now an example of iter_swap -- swap first 
    // and last elements.
    std::iter_swap (v.begin(), v.end () - 1);

    // Output result
    std::cout << "\n\nSwapping the first and last elements "
              << "gives: \n     ";
    std::copy (v.begin (), v.end (), Iter (std::cout, " "));

    std::cout << std::endl;

    return 0;
}


Program Output:

For the vector: 6 7 8 9 10 1 2 3 4 5 

Swapping the first five elements with the last five gives: 
     1 2 3 4 5 6 7 8 9 10 

Swapping the first and last elements gives: 
     10 2 3 4 5 6 7 8 9 1 

iter_swap(), swap()

ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.2