Q156618: STL Sample for the count Function

Article: Q156618
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s): 
Keyword(s): _IK
Last Modified: 07-MAY-2001

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The information in this article applies to:

- The Standard C++ Library, included with:
   - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, version 4.2 
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SUMMARY
=======

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

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

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

  <algorithm>
   

Prototype
---------

     template<class InputIterator, class T> inline
  </FIXEDTEXT>
  <BLOCKQUOTE>
     template<class InputIterator, class T> inline
         size_t count(InputIterator first,
                                          InputIterator 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 count algorithm counts the number of elements in the range [first, last +1)
that match value and returns the number of matching elements.

Sample Code
-----------

  ////////////////////////////////////////////////////////////////////// 
  // 
  // Compile options needed: /GX
  // 
  // count.cpp : Illustrates how to use the count function.
  // 
  // Functions:
  // 
  //    count  - Count items in a range that match a value.
  // 
  // 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
  #pragma warning(disable: 4786)

  #include <iostream>
  #include <algorithm>
  #include <functional>
  #include <string>
  #include <vector>
  using namespace std;

  void main()
  {
      const int VECTOR_SIZE = 8 ;

      // Define a template class vector of strings
      typedef vector<string, allocator<string> > StringVector ;

      //Define an iterator for template class vector of strings
      typedef StringVector::iterator StringVectorIt ;

      StringVector NamesVect(VECTOR_SIZE) ;   //vector containing names

      string value("Sea") ;  // stores the value used
                             // to count matching elements

      StringVectorIt start, end, it ;

      int result = 0 ;   // stores count of elements
                         // that match value.

      // Initialize vector NamesVect
      NamesVect[0] = "She" ;
      NamesVect[1] = "Sells" ;
      NamesVect[2] = "Sea" ;
      NamesVect[3] = "Shells" ;
      NamesVect[4] = "by" ;
      NamesVect[5] = "the" ;
      NamesVect[6] = "Sea" ;
      NamesVect[7] = "Shore" ;

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

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

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

      // Count the number of elements in the range [first, last +1)
      // that match value.
      result = count(start, end, value) ;

      // print the count of elements that match value
      cout << "Number of elements that match \"Sea\" = "
          << result << endl  ;
  }

Program Output is:

NamesVect { She Sells Sea Shells by the Sea Shore }

Number of elements that match "Sea" = 2

REFERENCES
==========

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

Additional query words: STL count

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

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