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  1. #include<vector>
  2. #include<chrono>
  3. #include<iostream>
  4. #include<memory>
  5. #include<iomanip>
  6.  
  7. constexpr size_t size = 10'000'000;
  8. constexpr size_t reps = 50;
  9.  
  10. auto time_vector() {
  11. 	auto start = std::chrono::steady_clock::now();
  12. 	{
  13. 		std::vector<double> a(size);
  14. 		std::vector<double> b(size);
  15. 		std::vector<double> c(size);
  16.  
  17. 		for (size_t t = 0; t < reps; t++) {
  18. 			for (size_t i = 0; i < size; i++) {
  19. 				c[i] = a[i] + b[i];
  20. 			}
  21. 		}
  22. 	}
  23. 	auto end = std::chrono::steady_clock::now();
  24. 	return end - start;
  25. }
  26.  
  27. auto time_pointer() {
  28. 	auto start = std::chrono::steady_clock::now();
  29. 	{
  30. 		double * a = new double[size];
  31. 		double * b = new double[size];
  32. 		double * c = new double[size];
  33.  
  34. 		for (size_t t = 0; t < reps; t++) {
  35. 			for (size_t i = 0; i < size; i++) {
  36. 				c[i] = a[i] + b[i];
  37. 			}
  38. 		}
  39.  
  40. 		delete[] a;
  41. 		delete[] b;
  42. 		delete[] c;
  43. 	}
  44. 	auto end = std::chrono::steady_clock::now();
  45. 	return end - start;
  46. }
  47.  
  48. auto time_unique_ptr() {
  49. 	auto start = std::chrono::steady_clock::now();
  50. 	{
  51. 		std::unique_ptr<double[]> a = std::make_unique<double[]>(size);
  52. 		std::unique_ptr<double[]> b = std::make_unique<double[]>(size);
  53. 		std::unique_ptr<double[]> c = std::make_unique<double[]>(size);
  54.  
  55. 		for (size_t t = 0; t < reps; t++) {
  56. 			for (size_t i = 0; i < size; i++) {
  57. 				c[i] = a[i] + b[i];
  58. 			}
  59. 		}
  60. 	}
  61. 	auto end = std::chrono::steady_clock::now();
  62. 	return end - start;
  63. }
  64.  
  65. int main() {
  66. 	std::cout << "Vector took         " << std::setw(12) << time_vector().count() << "ns" << std::endl;
  67. 	std::cout << "Pointer took        " << std::setw(12) << time_pointer().count() << "ns" << std::endl;
  68. 	std::cout << "Unique Pointer took " << std::setw(12) << time_unique_ptr().count() << "ns" << std::endl;
  69. 	return 0;
  70. }
Success #stdin #stdout 3.24s 15232KB
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stdin
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Standard input is empty
stdout
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Vector took           1442575273ns
Pointer took           542265103ns
Unique Pointer took   1280087558ns
https://ideone.com/ErYWcS
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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