How to get min or max element in a vector of structures in c++, based on some field in the structure?

Question

How to get min or max element in a vector of structures in c++, based on some field in the structure?

For example:

struct Size {
    int width, height;
}         


        

Answer 1

Solution using std::minmax_element with lambda expression:

#include 
#include 

struct Size {
    int width, height;
};

int main()
{
     std::vector sizes;

     sizes.push_back({4,1});
     sizes.push_back({2,3});
     sizes.push_back({1,2});

     auto minmax_widths = std::minmax_element(sizes.begin(), sizes.end(),
         [] (Size const& lhs, Size const& rhs) {return lhs.width < rhs.width;});
     auto minmax_heights = std::minmax_element(sizes.begin(), sizes.end(),
         [] (Size const& lhs, Size const& rhs) {return lhs.height < rhs.height;});

     std::cout << "Minimum (based on width): " << minmax_widths.first->width << std::endl;
     std::cout << "Maximum (based on width): " << minmax_widths.second->width << std::endl;

     std::cout << "Minimum (based on height): " << minmax_heights.first->height << std::endl;
     std::cout << "Maximum (based on height): " << minmax_heights.second->height << std::endl;
}