iter_swap (STL Sample)

The sample code below illustrates how to use the iter_swap STL function in Visual C++.

Required Header:
<algorithm>

template<class ForwardIterator1, class ForwardIterator2> inline
     void iter_swap(ForwardIterator1 first, ForwardIterator2 second)

Note: The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.

Description:
The iter_swap algorithm swaps two elements represented by two iterators.

Sample Code:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// iter_swap.cpp : Illustrates how to use the iter_swap function.
//
// Functions:
//
//   iter_swap  - Swap two elements in a sequence represented by
//                two iterators.
//
//   begin      - Returns an iterator that points to the first element
//                in a sequence.
//
//   end        - Returns an iterator that points one past the end of
//                  a sequence.
//////////////////////////////////////////////////////////////////////

// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;


// return the next Fibonacci number in the
// Fibonacci series.
int Fibonacci(void)
{
    static int r;
    static int f1 = 0;
    static int f2 = 1;
    r = f1 + f2 ;
    f1 = f2 ;
    f2 = r ;
    return f1 ;
}

void main()
{
    const int VECTOR_SIZE = 8 ;

    // Define a template class vector of integers
    typedef vector<int > IntVector ;

    //Define an iterator for template class vector of integer
    typedef IntVector::iterator IntVectorIt ;

    IntVector Numbers(VECTOR_SIZE) ;   //vector containing numbers

    IntVectorIt start, end, it ;

    start = Numbers.begin() ;   // location of first
                                // element of Numbers

    end = Numbers.end() ;       // one past the location
                                // last element of Numbers

    // fill the range [first, last +1) with a series of
    // Fibonacci numbers using the Fibonacci function
    generate(start, end, Fibonacci) ;

    cout << "Before calling iter_swap" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // swap the first and last elements of the
    // sequence using iter_swap
    iter_swap(start, end - 1) ;

    cout << "After calling iter_swap" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

}

 

Program Output is:

Before calling iter_swap
Numbers { 1 1 2 3 5 8 13 21  }

After calling iter_swap
Numbers { 21 1 2 3 5 8 13 1  }