How to create a std::set with custom comparator in C++?

Question

How do I create a set of pairs, the elements of which (the pairs) are sorted with a custom bool function? I write

set ,compare> my         


        

Answer 1

You should use a functional object. Here is an example

#include 
#include 
#include 

struct Compare
{
    bool operator ()( const std::pair &p1, 
                      const std::pair &p2 ) const
    {
        return ( p1.second - p1.first  > p2.second - p2.first );
    }
};

int main() 
{
    std::set, Compare> s;

    return 0;
}