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multimap::value_comp

The member function returns a function object that determines the order of elements in a multimap by comparing their key values.

value_compare value_comp( ) const;

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

For a multimap m, if two elements e1(k1, d1) and e2(k2, d2) are objects of type value_type, where k1 and k2 are their keys of type key_type and d1 and d2 are their data of type mapped_type, then m.value_comp(e1, e2) is equivalent to m.key_comp(k1, k2).

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

int main( )
{
   using namespace std;
   
   multimap <int, int, less<int> > m1;
   multimap <int, int, less<int> >::value_compare vc1 = m1.value_comp( );
   multimap<int,int>::iterator Iter1, Iter2;
   
   Iter1= m1.insert ( multimap <int, int> :: value_type ( 1, 10 ) );
   Iter2= m1.insert ( multimap <int, int> :: value_type ( 2, 5 ) );

   if( vc1( *Iter1, *Iter2 ) == true )   
   {
      cout << "The element ( 1,10 ) precedes the element ( 2,5 )."
           << endl;
   }
   else   
   {
      cout << "The element ( 1,10 ) does "
           << "not precede the element ( 2,5 )."
           << endl;
   }

   if( vc1( *Iter2, *Iter1 ) == true )   
   {
      cout << "The element ( 2,5 ) precedes the element ( 1,10 )."
           << endl;
   }
   else   
   {
      cout << "The element ( 2,5 ) does "
           << "not precede the element ( 1,10 )."
           << endl;
   }
}
The element ( 1,10 ) precedes the element ( 2,5 ).
The element ( 2,5 ) does not precede the element ( 1,10 ).

Header: <map>

Namespace: std

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