fork download
copy 
  1. #include <vector>
  2. #include <string>
  3. #include <algorithm>
  4. #include <iostream>
  5. #include <numeric>
  6. #include <chrono>
  7.  
  8. struct Point {
  9.    double x = {}, y = {}, z = {};
  10.    Point() = default;
  11.    Point(double x, double y, double z) : x{ x }, y{ y }, z{ z } {
  12.    }
  13. };
  14. int main() {
  15.    using namespace std;
  16.    using namespace std::chrono;
  17.    // la destination: un vecteur
  18.    enum { NTESTS = 50 };
  19.    enum { NELEMS = 10'000'000 };
  20.    milliseconds elapsed_push[NTESTS]{};
  21.    vector<Point> v;
  22.    v.reserve(NELEMS);
  23.    for (int i = 0; i < NTESTS; ++i) {
  24.       v.clear();
  25.       auto avant = high_resolution_clock::now();
  26.       for (int j = 0; j < NELEMS; ++j)
  27.          v.push_back(Point{ 1.0, -1.0, 1.0 });
  28.       auto apres = high_resolution_clock::now();
  29.       elapsed_push[i] = duration_cast<milliseconds>(apres - avant);
  30.    }
  31.    milliseconds elapsed_emplace[NTESTS]{};
  32.    for (int i = 0; i < NTESTS; ++i) {
  33.       v.clear();
  34.       auto avant = high_resolution_clock::now();
  35.       for (int j = 0; j < NELEMS; ++j) {
  36.          v.emplace_back(1.0, -1.0, 1.0);
  37.       }
  38.       auto apres = high_resolution_clock::now();
  39.       elapsed_emplace[i] = duration_cast<milliseconds>(apres - avant);
  40.    }
  41.    sort(begin(elapsed_push), end(elapsed_push));
  42.    auto moyenne_push = accumulate(begin(elapsed_push), end(elapsed_push), milliseconds{}) / static_cast<double>(NTESTS);
  43.    auto moyenne_emplace = accumulate(begin(elapsed_emplace), end(elapsed_emplace), milliseconds{}) / static_cast<double>(NTESTS);
  44.    cout << "Avec " << NTESTS << " tests de push_back() sur " << NELEMS << " elements:\n"
  45.       << "\tmeilleur temps: " << elapsed_push[0].count() << " ms.\n"
  46.       << "\tpire temps: " << elapsed_push[NTESTS - 1].count() << " ms.\n"
  47.       << "\ttemps moyen: " << moyenne_push.count() << " ms.\n" << endl;
  48.    sort(begin(elapsed_emplace), end(elapsed_emplace));
  49.    cout << "Avec " << NTESTS << " tests de emplace() sur " << NELEMS << " elements:\n"
  50.       << "\tmeilleur temps: " << elapsed_emplace[0].count() << " ms.\n"
  51.       << "\tpire temps: " << elapsed_emplace[NTESTS - 1].count() << " ms.\n"
  52.       << "\ttemps moyen: " << moyenne_emplace.count() << " ms.\n" << endl;
  53.    cout << "Pour esssentiellement le meme travail,\n"
  54.       << "emplace_back() requiert en moyenne "
  55.       << moyenne_emplace / moyenne_push * 100.0
  56.       << "% du temps requis par push_back()\n" << endl;
  57. }
  58.  
Success #stdin #stdout 3.63s 15240KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Avec 50 tests de push_back() sur 10000000 elements:
	meilleur temps: 34 ms.
	pire temps: 63 ms.
	temps moyen: 36.76 ms.

Avec 50 tests de emplace() sur 10000000 elements:
	meilleur temps: 33 ms.
	pire temps: 40 ms.
	temps moyen: 34.94 ms.

Pour esssentiellement le meme travail,
emplace_back() requiert en moyenne 95.049% du temps requis par push_back()
https://ideone.com/akJQMa
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!