20.1 InstantiatingMapMultimap.cpp

#include<map>
#include<string>

template<typename keyType>
struct ReverseSort
{
  bool operator()(const keyType& key1, const keyType& key2)
   {
      return (key1 > key2);
   }
};

int main ()
{
   using namespace std;

   // map and multimap key of type int to value of type string
   map<int, string> mapIntToStr1;
   multimap<int, string> mmapIntToStr1;

   // map and multimap constructed as a copy of another
   map<int, string> mapIntToStr2(mapIntToStr1);
   multimap<int, string> mmapIntToStr2(mmapIntToStr1);

   // map and multimap constructed given a part of another map or multimap
   map<int, string> mapIntToStr3(mapIntToStr1.cbegin(),
                                    mapIntToStr1.cend());

   multimap<int, string> mmapIntToStr3(mmapIntToStr1.cbegin(),
                                          mmapIntToStr1.cend());

   // map and multimap with a predicate that inverses sort order
   map<int, string, ReverseSort<int> > mapIntToStr4
      (mapIntToStr1.cbegin(), mapIntToStr1.cend());

   multimap<int, string, ReverseSort<int> > mmapIntToStr4
      (mapIntToStr1.cbegin(), mapIntToStr1.cend());

   return 0;
}