The sample code below illustrates how to use the lower_bound
STL function in Visual C++.
Required Header:
<algorithm>
template<class ForwardIterator, class T>
inline ForwardIterator lower_bound(ForwardIterator first, ForwardIterator last, const T& value)
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 lower_bound algorithm returns the first location in the sequence that value can be inserted such that the order of the sequence is maintained. lower_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. lower_bound assumes the range [first..last) is sorted using operator<.
Sample Code:
//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// lower_bound.cpp : Illustrates how to use the lower_bound
// function.
//
// Functions:
//
// lower_bound : Return the lower bound within a range.
//////////////////////////////////////////////////////////////////////
// disable warning C4786: symbol greater than 255 character,
// okay to ignore this warning
#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] = 10 ;
Numbers[3] = 30 ;
Numbers[4] = 69 ;
Numbers[5] = 70 ;
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
// print content of Numbers
cout << "Numbers { " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
// return the first location at which 10 can be inserted
// in Numbers
location = lower_bound(start, end, 10) ;
cout << "First location element 10 can be inserted in Numbers is: "
<< location - start << endl ;
}
Program Output is:
Numbers { 4 10 10 30 69 70 96 100 }
First location element 10 can be inserted in Numbers is: 1