Comparator for min-heap in C++

Question

I am trying to make a min-heap¹ of longs in C++ using the STL make_heap, etc., but my comparator doesn't seem to be comparing properly. The following is my current comparator:

struct greater1{
    bool operator()(const long& a,const long& b) const{
        return a>b;
    }
};

However, when I do std::pop_heap(humble.begin(),humble.end(),g); where g is an instance of greater1 and humble is a heap who makes [9,15,15,25] when sort_heap is called, I get a 15 popped.

Is my comparator correct? what might be going wrong?

EDIT:
I realized that I am running sort_heap with no comparator, whereas when I run it this comparator, I get [15,15,9,25] from sort_heap. Now I am thinking my comparator is definitely not working, but unsure why.

¹The STL makes a max-heap by default, so I need a comparator.

Answer 1

Perhaps you are missing something somewhere, the code below works as intended:

#include <vector>
#include <algorithm>
#include <iostream>

struct greater1{
  bool operator()(const long& a,const long& b) const{
    return a>b;
  }
};

int main() {
  std::vector<long> humble;
  humble.push_back(15);
  humble.push_back(15);
  humble.push_back(9);
  humble.push_back(25);

  std::make_heap(humble.begin(), humble.end(), greater1());
  while (humble.size()) {
    std::pop_heap(humble.begin(),humble.end(),greater1());
    long min = humble.back();
    humble.pop_back();  
    std::cout << min << std::endl;
  }

  return 0;
}