Information
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

map::key_comp

Retrieves a copy of the comparison object used to order keys in a map.

key_compare key_comp( ) const;

Returns the function object that a map uses to order its elements.

The stored object defines the member function

bool operator(const Key& _Left, const Key& _Right);

which returns true if _Left precedes and is not equal to _Right in the sort order.

// map_key_comp.cpp
// compile with: /EHsc
#include <map>
#include <iostream>

int main( )
{
   using namespace std;
   
   map <int, int, less<int> > m1;
   map <int, int, less<int> >::key_compare kc1 = m1.key_comp( ) ;
   bool result1 = kc1( 2, 3 ) ;
   if( result1 == true )
   {
      cout << "kc1( 2,3 ) returns value of true, "
           << "where kc1 is the function object of m1."
           << endl;
   }
   else   
   {
      cout << "kc1( 2,3 ) returns value of false "
           << "where kc1 is the function object of m1."
           << endl;
   }

   map <int, int, greater<int> > m2;
   map <int, int, greater<int> >::key_compare kc2 = m2.key_comp( );
   bool result2 = kc2( 2, 3 ) ;
   if( result2 == true )
   {
      cout << "kc2( 2,3 ) returns value of true, "
           << "where kc2 is the function object of m2."
           << endl;
   }
   else   
   {
      cout << "kc2( 2,3 ) returns value of false, "
           << "where kc2 is the function object of m2."
           << endl;
   }
}
kc1( 2,3 ) returns value of true, where kc1 is the function object of m1.
kc2( 2,3 ) returns value of false, where kc2 is the function object of m2.

Header: <map>

Namespace: std

Show:
© 2014 Microsoft