set::count (STL Sample)

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

Required Header:
<set>

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 do 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:

//////////////////////////////////////////////////////////////////////
//
// 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.
//////////////////////////////////////////////////////////////////////

#pragma warning(disable:4786)
#include <set>
#include <iostream>

using namespace std ;

typedef set<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 is:

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