如何指定配对比较？

pair

pair <string, int> myPair;

pair

make_heap

I know I need something like this for heap to operate. But not sure where to put it:

bool operator< (const Pair& p1, const Pair& p2) const 
{ 
    return p1.second < p2.second;
}

make_heap

// somewhere in global namespace
typedef std::pair<std::string, int> myPair_type;

struct mypair_comp{
  bool operator()(myPair_type const& lhs, myPair_type const& rhs){
    return lhs.second < rhs.second;
  }
};

// somewhere at your callside
make_heap(first,last,mypair_comp());