swap_ranges()

Module:  Standard C++ Library   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

Copyright (c) 1994-2006 Rogue Wave Software, a Quovadx Division.
Licensed under the Apache License, Version 2.0.
Contact Rogue Wave about documentation or support issues. You can also seek help from other developers through the Apache stdcxx community (see below).