C++ std::map items in descending order of keys -

how cal use std::map container key value in descending order.

as example, if insert following items:

[2 , 5] [1 , 34] [3 , 67] 

they ordered in map like:

position 0: [1, 34] position 1: [2, 5] position 2: [3, 67] 

i can iterate through map reversely, suppose next time inserting [-1 , 60]. placed @ first position?

use custom comparator when default order doesn't you.
pass third template parameter ( that's defaulted std::less<keytype> ).
in case, can use std::greater:

std::map<int, int, std::greater<int> > m; 

example code:

#include <map> #include <iostream>  int main() {   std::map<int, int, std::greater<int>> m { {-1, 77}, {0, 42}, {1, 84} };   (const auto& p : m)     std::cout << '[' << p.first << ',' << p.second << "]\n"; } 

resulting output:

[1,84] [0,77] [-1,42]