rotate (STL Sample)

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

Required Header:
<algorithm>

template<class ForwardIterator> inline
     void rotate(ForwardIterator first,
     ForwardIterator middle,
     ForwardIterator last)

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 rotate algorithm rotates the elements in the range [first, last) to the right by N positions, where N = middle - first.

Sample Code:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// rotate.cpp : Illustrates how to use the rotate function.
//
// Functions:
//
//    rotate - Rotate the items in a sequence by n positions.
//
//////////////////////////////////////////////////////////////////////

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

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>

using namespace std ;

void main()
{
    const int VECTOR_SIZE = 8 ;

    // Define a template class vector of strings
    typedef vector<string> StrVector ;

    //Define an iterator for template class vector of strings
    typedef StrVector::iterator StrVectorIt ;

    StrVector Tongue_Twister(VECTOR_SIZE) ;

    StrVectorIt start, end, middle, it ;

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

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

    //Initialize vector Tongue_Twister
    Tongue_Twister[0] = "she" ;
    Tongue_Twister[1] = "sells" ;
    Tongue_Twister[2] = "sea" ;
    Tongue_Twister[3] = "shells" ;
    Tongue_Twister[4] = "by";
    Tongue_Twister[5] = "the";
    Tongue_Twister[6] = "sea" ;
    Tongue_Twister[7] = "shore" ;

    middle = start + 3 ;  // start position for rotating elements

    cout << "Before calling rotate\n" << endl ;

    // print content of Tongue_Twister
    cout << "Try this Tongue Twister: " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << "\n\n" ;

    // rotate the items in the vector Tongue_Twister by 3 positions
    rotate(start, middle, end) ;

    cout << "After calling rotate \n" << endl ;

    // print content of Tongue_Twister
    cout << "Now try the rotated Tongue Twister: " ;
    for(it = start; it != end; it++)
        cout << *it << " " ;
    cout << "\n\n" ;
}

 

Program Output is:

Before calling rotate

Try this Tongue Twister: she sells sea shells by the sea shore

After calling rotate

Now try the rotated Tongue Twister: shells by the sea shore she sells sea