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Returns the number of elements in a set whose key matches a parameter-specified key.
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
When compiling this example with the /Wp64 flag or on a 64-bit platform, compiler warning C4267 will be generated. For more information on this warning, see Compiler Warning (level 3) C4267.
// 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