STL Sample for the iter_swap Function

ID: Q156346

The information in this article applies to:

SUMMARY

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

MORE INFORMATION

Required Header

   <algorithm>

Prototype

   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.
// 
// Written by Kalindi Sanghrajka
// of Microsoft Product Support Services,
// Software Core Developer Support.
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
////////////////////////////////////////////////////////////////////// 

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

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

// 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, allocator<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 ;
}

The 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 }

REFERENCES

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL STLSample generate end begin 

Keywords          : kbcode STLIss 
Version           : WINNT:4.2;
Platform          : NT WINDOWS
Issue type        : kbhowto

Last Reviewed: October 10, 1997