Retrieves a copy of the comparison object used to order keys in a hash_map.
key_compare key_comp( ) const;
Return Value
Returns the function object that a hash_map uses to order its elements.
Remarks
The stored object defines the member function
bool operator(const Key& _Left**, const Key&** _Right);
that returns true if _Left precedes and is not equal to _Right in the sort order.
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
// hash_map_key_comp.cpp
// compile with: /EHsc
#define _DEFINE_DEPRECATED_HASH_CLASSES 0
#include <hash_map>
#include <iostream>
int main( )
{
using namespace std;
using namespace stdext;
hash_map <int, int, hash_compare<int, less<int> > > hm1;
hash_map <int, int, hash_compare<int, less<int> > >::key_compare
kc1 = hm1.key_comp( ) ;
// Operator stored in kc1 tests order & returns bool value
bool result1 = kc1( 2, 3 ) ;
if( result1 == true )
{
cout << "kc1( 2,3 ) returns value of true,"
<< "\n where kc1 is the function object of hm1"
<< " of type key_compare." << endl;
}
else
{
cout << "kc1( 2,3 ) returns value of false"
<< "\n where kc1 is the function object of hm1"
<< " of type key_compare." << endl;
}
hash_map <int, int, hash_compare<int, greater<int> > > hm2;
hash_map <int, int, hash_compare<int, greater<int> > >
::key_compare kc2 = hm2.key_comp( );
// Operator stored in kc2 tests order & returns bool value
bool result2 = kc2( 2, 3 ) ;
if( result2 == true )
{
cout << "kc2( 2,3 ) returns value of true,"
<< "\n where kc2 is the function object of hm2"
<< " of type key_compare." << endl;
}
else
{
cout << "kc2( 2,3 ) returns value of false,"
<< "\n where kc2 is the function object of hm2"
<< " of type key_compare." << endl;
}
}
Output
kc1( 2,3 ) returns value of true,
where kc1 is the function object of hm1 of type key_compare.
kc2( 2,3 ) returns value of false,
where kc2 is the function object of hm2 of type key_compare.
Requirements
Header: <hash_map>
Namespace: stdext