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  1. #include <iostream>
  2. #include <map>
  3.  
  4. struct Data {
  5.     int numFriends = 0, numAcquaintances = 0, numDates = 0;  // etc...
  6. };
  7.  
  8. void print_tabbed(std::ostream& os, const Data& d)
  9. {
  10.     os << '\t' << d.numAcquaintances << " acquaintances\n";
  11.     os << '\t' << d.numDates << " dates\n";
  12.     os << '\t' << d.numFriends << " friends\n";
  13. }
  14.  
  15. enum Country { USA, Canada, France };
  16. enum Personality { Serious, Lazy, Funny };
  17.  
  18. class Religion {} *Islam = new Religion, *Hindu = new Religion;
  19.  
  20. class Person {
  21. private:
  22.     std::map<Country, Data> countryStats;
  23.     std::map<Personality, Data> personalityStats;
  24.     std::map<Religion*, Data> religionStats;
  25.  
  26.     // overloads
  27.     std::map<Country, Data>&     statsMap(const Country&)     { return countryStats; }
  28.     std::map<Personality, Data>& statsMap(const Personality&) { return personalityStats; }
  29.     std::map<Religion*, Data>&   statsMap(const Religion*)    { return religionStats; }
  30.  
  31. public:
  32.     template<typename T>
  33.     void insert(const T& key, int Data::*dataPtr, int num) 
  34.     {     
  35.         statsMap(key)[key].*dataPtr += num; 
  36.     }
  37.  
  38.     template<typename T>
  39.     void insertData(const T& key, const Data& data) { statsMap(key)[key] = data; }
  40.  
  41.     template <typename map_type>
  42.     void print_map(std::ostream& os, map_type& m, bool blank_line = true)
  43.     {
  44.         for (auto& e : m)
  45.         {
  46.             os << e.first << '\n';
  47.             print_tabbed(os, e.second);
  48.         }
  49.  
  50.         if (!m.empty() && blank_line)
  51.             os << '\n';
  52.     }
  53.  
  54.     void showAllStats() {  // for testing the results only (but only works for Country)
  55.         print_map(std::cout, countryStats);
  56.         print_map(std::cout, personalityStats);
  57.         print_map(std::cout, religionStats, false);
  58.  
  59.         std::cout << '\n';
  60.     }
  61. };
  62.  
  63. int main() {
  64.     Person bob, sam;
  65.  
  66.     bob.insert(USA, &Data::numFriends, 10);
  67.     bob.insert(Canada, &Data::numFriends, 100);
  68.     bob.insert(Canada, &Data::numDates, 5);
  69.     sam.insert(USA, &Data::numFriends, 30);
  70.     sam.insert(USA, &Data::numAcquaintances, 50);
  71.  
  72.     bob.insert (Funny, &Data::numAcquaintances, 20);  // won't compile
  73.     sam.insert (Islam, &Data::numAcquaintances, 35);  // won't compile
  74.     std::cout << "Bob:" << std::endl;  bob.showAllStats();  // correct results, but only for Country
  75.     std::cout << "Sam:" << std::endl;  sam.showAllStats();
  76.     std::cin.get();
  77. }
Success #stdin #stdout 0s 3480KB
comments (?)
stdin
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Standard input is empty
stdout
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Bob:
0
	0 acquaintances
	0 dates
	10 friends
1
	0 acquaintances
	5 dates
	100 friends

2
	20 acquaintances
	0 dates
	0 friends


Sam:
0
	50 acquaintances
	0 dates
	30 friends

0x96b1008
	35 acquaintances
	0 dates
	0 friends
https://ideone.com/rkMmaW
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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