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  1.     #include <map>
  2.     #include <string>
  3.     #include <algorithm>
  4.     #include <iterator>
  5.     #include <iostream>
  6.  
  7.     // define the Sorter template class.  If sortdir == true, then we sort ascending
  8.     template <bool sortdir = true>
  9.     struct Sorter
  10.     {
  11.         bool operator()(const std::string& left, const std::string& right)
  12.         {
  13.             if ( sortdir )
  14.                 return left < right;
  15.             return left > right;
  16.         }
  17.     };
  18.  
  19.     // our test maps
  20.     typedef std::pair<unsigned long long, unsigned long long> mapDataType;
  21.  
  22.     // ascending map
  23.     std::map<std::string, mapDataType, Sorter<>> myMap = {{"abc", {0,0}}, {"def",{0,1}}};  
  24.  
  25.     // descending map
  26.     std::map<std::string, mapDataType, Sorter<false>> myMap2; // descending map
  27.  
  28.     // sample program    
  29.     using namespace std;
  30.     int main() 
  31.     {
  32.         // copy to descending map 
  33.         std::copy(myMap.begin(), myMap.end(), std::inserter(myMap2, myMap2.begin()));
  34.  
  35.         cout << "The keys in ascending map are:\n";
  36.         for (auto it : myMap)
  37.         	cout << it.first << "\n";
  38.         cout << "\nThe keys in descending map are:\n";
  39.         for (auto it : myMap2)
  40.         	cout << it.first << "\n";
  41.  
  42.     }
  43.  
Success #stdin #stdout 0s 3460KB
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Standard input is empty
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The keys in ascending map are:
abc
def

The keys in descending map are:
def
abc
https://ideone.com/LEHOzd
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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