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  1. #include <iostream>
  2. #include <chrono>
  3. #include <string>
  4. #include <map>
  5. #include <cstdint>
  6. #include <ctime>
  7. #include <random>
  8. #include <algorithm>
  9. #include <utility>
  10.  
  11. class Elapsed {
  12.   std::chrono::high_resolution_clock::time_point firstTime;
  13.   std::string mes;
  14. public:
  15.   Elapsed(const std::string& s) : mes(s) {
  16.     firstTime = std::chrono::high_resolution_clock::now();
  17.   }
  18.   ~Elapsed() {
  19.     std::cout << mes << std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::high_resolution_clock::now() - firstTime).count() << "ms" << std::endl;
  20.   }
  21. };
  22.  
  23. class Heavy {
  24.   static const int N = 100000;
  25.   double* d;
  26. public:
  27.   Heavy() : d(new double[N]) {}
  28.   Heavy(const Heavy& h) { // copy constructor
  29.     d = new double[N];
  30.     std::copy(h.d, h.d + N, d);
  31.   }
  32. //  Heavy(Heavy&& h) { // move constructor
  33. //    d = h.d;
  34. //    h.d = nullptr;
  35. //  }
  36.   ~Heavy() { delete[] d; }
  37. };
  38.  
  39. const int ITER = 100;
  40. const int NSEEDS = 10;
  41.  
  42. int main()
  43. {
  44.   typedef std::map<double, Heavy> MDH;
  45.   MDH m;
  46.  
  47.   std::uint32_t seeds[NSEEDS];
  48.   auto t = std::time(nullptr);
  49.  
  50.   for (std::size_t i = 0; i < NSEEDS; i++)
  51.     if (seeds[i] == 0)
  52.       seeds[i] = t * (i + 3) ;
  53.  
  54.   std::seed_seq seed_seq(seeds, seeds + NSEEDS);
  55.   std::mt19937 twister(seed_seq);
  56.   std::uniform_real_distribution<> dist(0.0, 10000.0);
  57.  
  58.   {
  59.     Elapsed ep("value_type = ");
  60.  
  61.     for (int i = 0; i < ITER; i++)
  62.       m.insert(MDH::value_type(dist(twister), Heavy()));
  63.   }
  64.   m.clear();
  65.   {
  66.     Elapsed ep("std::pair = ");
  67.  
  68.     for (int i = 0; i < ITER; i++)
  69.       m.insert(std::pair<double, Heavy>(dist(twister), Heavy()));
  70.   }
  71.   m.clear();
  72.   {
  73.     Elapsed ep("std::make_pair = ");
  74.  
  75.     for (int i = 0; i < ITER; i++)
  76.       m.insert(std::make_pair(dist(twister), Heavy()));
  77.   }
  78.   m.clear();
  79.   {
  80.     Elapsed ep("std::emplace = ");
  81.  
  82.     for (int i = 0; i < ITER; i++)
  83.       m.emplace(dist(twister), Heavy());
  84.   }
  85. }
  86.  
Success #stdin #stdout 0.6s 3480KB
comments (?)
stdin 
Standard input is empty
stdout 
value_type = 165ms
std::pair = 165ms
std::make_pair = 164ms
std::emplace = 92ms
https://ideone.com/hTjhtc
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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