KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q157221: STL Sample for the Predicate Version of lower_bound Function

Article: Q157221
Product(s): Microsoft C Compiler
Version(s): winnt:4.2
Operating System(s): 
Keyword(s): _IK
Last Modified: 06-MAY-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- The Standard C++ Library 
- Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
- Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
-------------------------------------------------------------------------------

SUMMARY
=======

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

MORE INFORMATION
================

Required Header
---------------

     <algorithm>

Prototype
---------

     template<class ForwardIterator, class T, class Compare> inline
         ForwardIterator lower_bound(ForwardIterator first,
                                       ForwardIterator last,
                                       const T& value,
                                       Compare compare)

NOTE: The class/parameter names in the prototype do not match the original
version in the header file. They 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.

This version assumes the range [first..last) is sorted sequentially using the
compare function.

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.
  // 
  // 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 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, allocator<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>()
      //lower_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 first location at which 10 can be inserted
      // in Numbers
      location = lower_bound(start, end, 10, less<int>()) ;

      cout << "First location element 10 can be inserted in Numbers is: "
          << location - start << endl ;
  }

Output:

Numbers { 4 10 10 30 69 70 96 100  }

First location element 10 can be inserted in Numbers is: 1

REFERENCES
==========

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

Additional query words: STL lower_bound

======================================================================
Keywords          : _IK 
Technology        : kbVCsearch kbAudDeveloper kbVC420 kbVC32bitSearch kbVCLibrary
Version           : winnt:4.2
Issue type        : kbhowto

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.