About map custom sorting of keys

The map sorts the keys from small to large by default

You can also customize the sorting

#include
#include

// Define your own std::map comparator
template
struct PLess
{
// functor for operator<
bool operator()(const _Ty& pLeft, const _Ty& pRight) const
{
// apply operator< to operands
// return pLeft > pRight; // where this comparator differs from the default comparator
// }
};

int main()
{
// If Key is a pointer, in order to sort correctly, you need to define your own comparator object
std::map> datas;

datas[1] = 3;
datas[2] = 2;
datas[3] = 1;

return 0;
}