Predicate Version of inplace_merge (STL Sample)

The sample code below illustrates how to use the predicate version of the inplace_merge STL function in Visual C++.

Required Header:
<algorithm>

template<class BidirectionalIterator, class Compare> inline
     void inplace_merge(BidirectionalIterator first, BidirectionalIterator middle,
     BidirectionalIterator last, Compare compare)

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 inplace_merge algorithm merges two sorted sub-sequences: [first..middle) and [middle..last) in place into a single sorted sequence [first..last). This version assumes that the ranges [first..middle) and [middle..last) are sorted using the compare function. If both ranges contain equal values, the value from the first range will be stored first.

Sample Code:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// inplace_mergeP.cpp : Illustrates how to use the predicate version of
//                      the inplace_merge function.
//
// Functions:
//
//    inplace_merge - Merge two sorted sub-sequences in place into a
//                    single sorted list using the compare function.
//
//    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 <algorithm>
#include <functional>
#include <vector>

using namespace std;


void main()
{
    const int VECTOR_SIZE = 8 ;

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

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

    IntVector Numbers(VECTOR_SIZE) ;

    IntVectorIt start, end, it ;

    // Initialize vector Numbers
    Numbers[0] = 4 ;
    Numbers[1] = 10;
    Numbers[2] = 70 ;
    Numbers[3] = 10 ;
    Numbers[4] = 30 ;
    Numbers[5] = 69 ;
    Numbers[6] = 96 ;
    Numbers[7] = 100;

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

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

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

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

    //merge the elements of Numbers in place
    inplace_merge(start, start + 3, end, less<int>()) ;

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

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

 

Program Output is:

Before calling inplace_merge

Numbers { 4 10 70 10 30 69 96 100  }

After calling inplace_merge

Numbers { 4 10 10 30 69 70 96 100  }