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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. 		for(size_t i = 0; i < size; i++) a[i] = 0;
  15. 		std::vector<double> b(size);
  16. 		for(size_t i = 0; i < size; i++) b[i] = 0;
  17. 		std::vector<double> c(size);
  18. 		for(size_t i = 0; i < size; i++) c[i] = 0;
  19.  
  20. 		for (size_t t = 0; t < reps; t++) {
  21. 			for (size_t i = 0; i < size; i++) {
  22. 				c[i] = a[i] + b[i];
  23. 			}
  24. 		}
  25. 	}
  26. 	auto end = std::chrono::steady_clock::now();
  27. 	return end - start;
  28. }
  29.  
  30. auto time_pointer() {
  31. 	auto start = std::chrono::steady_clock::now();
  32. 	{
  33. 		double * a = new double[size];
  34. 		for(size_t i = 0; i < size; i++) a[i] = 0;
  35. 		double * b = new double[size];
  36. 		for(size_t i = 0; i < size; i++) b[i] = 0;
  37. 		double * c = new double[size];
  38. 		for(size_t i = 0; i < size; i++) c[i] = 0;
  39.  
  40. 		for (size_t t = 0; t < reps; t++) {
  41. 			for (size_t i = 0; i < size; i++) {
  42. 				c[i] = a[i] + b[i];
  43. 			}
  44. 		}
  45.  
  46. 		delete[] a;
  47. 		delete[] b;
  48. 		delete[] c;
  49. 	}
  50. 	auto end = std::chrono::steady_clock::now();
  51. 	return end - start;
  52. }
  53.  
  54. auto time_unique_ptr() {
  55. 	auto start = std::chrono::steady_clock::now();
  56. 	{
  57. 		std::unique_ptr<double[]> a = std::make_unique<double[]>(size);
  58. 		for(size_t i = 0; i < size; i++) a[i] = 0;
  59. 		std::unique_ptr<double[]> b = std::make_unique<double[]>(size);
  60. 		for(size_t i = 0; i < size; i++) b[i] = 0;
  61. 		std::unique_ptr<double[]> c = std::make_unique<double[]>(size);
  62. 		for(size_t i = 0; i < size; i++) c[i] = 0;
  63.  
  64. 		for (size_t t = 0; t < reps; t++) {
  65. 			for (size_t i = 0; i < size; i++) {
  66. 				c[i] = a[i] + b[i];
  67. 			}
  68. 		}
  69. 	}
  70. 	auto end = std::chrono::steady_clock::now();
  71. 	return end - start;
  72. }
  73.  
  74. int main() {
  75. 	std::cout << "Pointer took        " << std::setw(12) << time_pointer().count() << "ns" << std::endl;
  76. 	std::cout << "Vector took         " << std::setw(12) << time_vector().count() << "ns" << std::endl;
  77. 	std::cout << "Unique Pointer took " << std::setw(12) << time_unique_ptr().count() << "ns" << std::endl;
  78. 	return 0;
  79. }
Success #stdin #stdout 3.97s 15232KB
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stdin
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Standard input is empty
stdout
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Pointer took          1437017838ns
Vector took           1250983487ns
Unique Pointer took   1303497165ns
https://ideone.com/Q3wngz
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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