hash_set::count
Returns the number of elements in a hash_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 hash_set.
Return Value
1 if the hash_set contains an element whose sort key matches the parameter key.
0 if the hash_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 ) ).
In Visual C++ .NET 2003, members of the <hash_map> and <hash_set> header files are no longer in the std namespace, but rather have been moved into the stdext namespace. See The stdext Namespace for more information.
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.
// hash_set_count.cpp
// compile with: /EHsc
#define _DEFINE_DEPRECATED_HASH_CLASSES 0
#include <hash_set>
#include <iostream>
int main( )
{
using namespace std;
using namespace stdext;
hash_set<int> hs1;
hash_set<int>::size_type i;
hs1.insert(1);
hs1.insert(1);
// Keys must be unique in hash_set, so duplicates are ignored.
i = hs1.count(1);
cout << "The number of elements in hs1 with a sort key of 1 is: "
<< i << "." << endl;
i = hs1.count(2);
cout << "The number of elements in hs1 with a sort key of 2 is: "
<< i << "." << endl;
}
The number of elements in hs1 with a sort key of 1 is: 1. The number of elements in hs1 with a sort key of 2 is: 0.
Requirements
Header: <hash_set>
Namespace: stdext