set::count

Article
12/01/2015

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

Syntax

      size_type count(
   const Key& _Key
) const;

Parameters

_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

The following example demonstrates the use of the set::count member function.

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

int main()
{
    using namespace std;
    set<int> s1;
    set<int>::size_type 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;
}

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.

Requirements

Header: <set>

Namespace: std