How to use the set::count STL function in Visual C++ (158574)


The information in this article applies to:

  • The Standard C++ Library, when used with:
    • Microsoft Visual C++, 32-bit Enterprise Edition 4.2
    • Microsoft Visual C++, 32-bit Enterprise Edition 5.0
    • Microsoft Visual C++, 32-bit Enterprise Edition 6.0
    • Microsoft Visual C++, 32-bit Professional Edition 4.2
    • Microsoft Visual C++, 32-bit Professional Edition 5.0
    • Microsoft Visual C++, 32-bit Professional Edition 6.0
    • Microsoft Visual C++, 32-bit Learning Edition 6.0
    • Microsoft Visual C++ 2005 Express Edition
    • Microsoft Visual C++ .NET (2003)
    • Microsoft Visual C++ .NET (2002)
This article was previously published under Q158574
Note Microsoft Visual C++ .NET 2002 and Microsoft Visual C++ .NET 2003 support both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model. The information in this article applies only to unmanaged Visual C++ code. Microsoft Visual C++ 2005 supports both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model.

SUMMARY

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

MORE INFORMATION

Required Header

   <set>

Prototype

   template<class _K, class _Pr, class _A>
   class set {
   public:
   // Function 1:

      size_type count(const _K& _Kv) const;

   }
NOTE: The class/parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.

Description

The count function is used to determine the number of elements in the controlled sequence that have a particular key.

Sample Code

NOTE: The first line in the sample code section says:

// Compile options needed: /GX

In Visual C++ .NET and in Visual C++ 2005, /EHsc is set by default and is equivalent to /GX. 
////////////////////////////////////////////////////////////////////// 
// 
// Compile options needed: -GX
// 
// SetCount.cpp:
//      Illustrates how to use the count function to determine how
//      many elements have a particular key.
// 
// Functions:
// 
//    count        Returns the number of elements in the controlled
//                 sequence that have a particular key.
// 
// Written by Derek Jamison
// of Microsoft Technical Support,
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
////////////////////////////////////////////////////////////////////// 

#pragma warning(disable:4786)

// disable warning C4267: possible loss of data,
// okay to ignore

#pragma warning(disable: 4267)

#include <set>
#include <iostream>

#if _MSC_VER > 1020   // if VC++ version is > 4.2
   using namespace std;  // std c++ libs implemented in std
   #endif

typedef set<int,less<int>,allocator<int> > SET_INT;

void truefalse(int x)

{
  cout << (x?"True":"False") << endl;
}

void main() {

  SET_INT s1;
  SET_INT::_Pairib pib;
  cout << "s1.insert(5)" << endl;
  pib=s1.insert(5);
  cout << "Inserted element: ";
  truefalse(pib.second);  // True

  cout << "s1.insert(5)" << endl;
  pib=s1.insert(5);
  cout << "Inserted element: ";
  truefalse(pib.second);  // True

  cout << "s1.insert(8)" << endl;
  s1.insert(8);

  cout << "s1.insert(12)" << endl;
  s1.insert(12);

  cout << "s1.count(5) returned ";
  cout << s1.count(5) << endl;    // 1

  cout << "s1.count(9) returned ";
  cout << s1.count(9) << endl;    // 0
}

Program Output

s1.insert(5)
Inserted element: True
s1.insert(5)
Inserted element: False
s1.insert(8)
s1.insert(12)
s1.count(5) returned 1
s1.count(9) returned 0

REFERENCES

Visual C++ Books Online: Visual C++ Books; C/C++; Standard C++ Library Reference
Modification Type:MajorLast Reviewed:1/11/2006
Keywords:kbhowto kbcode kbinfo kbSTL kbtemplate KB158574 kbAudDeveloper
©2004 Microsoft Corporation. All rights reserved.