set::count

set::count

Visual Studio .NET 2003

其他版本

Returns the number of elements in a set whose key matches a parameter-specified key.

size_type count(
   const Key& _Key
) const;

Parameter

_Key

The key of the elements to be matched from the set.

Return Value

1 if the set contains an element whose sort key matches the parameter key. 0 if the set does not contain an element with a matching key.

Remarks

The member function returns the number of elements in the following range:

[lower_bound (_Key ), upper_bound (_Key ) ).

Example

// set_count.cpp
// compile with: /EHsc
#include <set>
#include <iostream>

int main( )
{
   using namespace std;   
   set <int> s1;
   int i;
   
   s1.insert( 1 );
   s1.insert( 1 );

   // Keys must be unique in set, so duplicates are ignored
   i = s1.count( 1 );
   cout << "The number of elements in s1 with a sort key of 1 is: "
        << i << "." << endl;

   i = s1.count( 2 );
   cout << "The number of elements in s1 with a sort key of 2 is: "
        << i << "." << endl;
}

Output

The number of elements in s1 with a sort key of 1 is: 1.
The number of elements in s1 with a sort key of 2 is: 0.