Predicate Version of upper_bound (STL Sample)

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

Required Header:
<algorithm>

template<class ForwardIterator, class T, class Compare> 
     inline orwardIterator upper_bound(ForwardIterator first, ForwardIterator last, 
     const T& value, 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 upper_bound algorithm returns the last location in the sequence that value can be inserted such that the order of the sequence [first..last) is maintained. upper_bound returns an iterator positioned at the location that value can be inserted in the range [first..last), or returns last if no such position exists. This version assumes the range [first..last) is sorted sequentially using the compare function.

Sample Code:

//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// upper_bound.cpp : Illustrates how to use the predicate version
//                   of the upper_bound function.
//
// Functions:
//
//    upper_bound : Return the upper bound within a range.

//////////////////////////////////////////////////////////////////////

// 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, location ;

    // 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

    //sort Numbers using the function object less<int>()
    //upper_bound assumes that Numbers is sorted
    //using the "compare" (less<int>() in this case)
    //function
    sort(start, end, less<int>()) ;

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

    //return the highest location at which 10 can be inserted
    // in Numbers
    location = upper_bound(start, end, 10, less<int>()) ;

    cout << "Last location  for element 10 in Numbers is: "
        << location - start << endl ;
}

 

Program Output is:

Numbers { 4 10 10 30 69 70 96 100  }

Last location  for element 10 in Numbers is: 3