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.