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  1.  
  2. #include <iostream>
  3. #include <iomanip>
  4. #include <windows.h>
  5.  
  6. using namespace std;
  7.  
  8. unsigned const gc_Rows = 1000, gc_Cols = 1000, gc_LoopCount = 2000;
  9. unsigned g_Data [gc_Rows][gc_Cols];
  10.  
  11. double TimerInvFrequency ()
  12. {
  13.     LARGE_INTEGER q;
  14. 	QueryPerformanceFrequency (&q);
  15. 	return 1.0 / q.QuadPart;
  16. }
  17.  
  18. double const gc_InvFreq = TimerInvFrequency ();
  19.  
  20. double ReadTime ()
  21. {
  22. 	LARGE_INTEGER q;
  23. 	QueryPerformanceCounter (&q);
  24. 	return q.QuadPart * gc_InvFreq;
  25. }
  26.  
  27. #define _BENCHMARK_BEGIN()						\
  28. {												\
  29. 	double _min = 1000, _max = 0, _total = 0;	\
  30. 	for (unsigned n = 0; n < gc_LoopCount; ++n)	\
  31. 	{											\
  32. 		double t0 = ReadTime ();				\
  33.  
  34.  
  35. #define _BENCHMARK_END(case_name)				\
  36. 		double dt = ReadTime() - t0;			\
  37. 												\
  38. 		_total += dt;							\
  39. 		if (dt < _min) _min = dt;				\
  40. 		if (dt > _max) _max = dt;				\
  41. 	}											\
  42. 	cout << case_name << ": "					\
  43. 		<< "min:" << fixed << setprecision(6) << _min								\
  44. 		<< ", " << "avg:" << fixed << setprecision(6) << (_total / gc_LoopCount)	\
  45. 		<< ", " << "max:" << fixed << setprecision(6) << _max						\
  46. 		<< endl;								\
  47. }												\
  48.  
  49.  
  50. int main ()
  51. {
  52. 	// Fill the data arrays
  53. 	for (unsigned i = 0, v = 0; i < gc_Rows; ++i)
  54. 		for (unsigned j = 0; j < gc_Cols; ++j, ++v)
  55. 			g_Data[i][j] = v;
  56.  
  57. 	// Simple iteration
  58. 	_BENCHMARK_BEGIN()
  59. 		volatile unsigned sum = 0;
  60. 		for (unsigned i = 0; i < gc_Rows; ++i)
  61. 			for (unsigned j = 0; j < gc_Cols; ++j)
  62. 				sum += g_Data[i][j];
  63. 	_BENCHMARK_END("Simple iteration (nested loops)")
  64.  
  65. 	_BENCHMARK_BEGIN()
  66. 		volatile unsigned sum = 0;
  67. 		for (unsigned i = 0; i < gc_Rows * gc_Cols; ++i)
  68. 				sum += g_Data[i / gc_Cols][i % gc_Cols];
  69. 	_BENCHMARK_END("    Simple iteration (one loop)")
  70.  
  71. 	_BENCHMARK_BEGIN()
  72. 		volatile unsigned sum = 0;
  73. 		unsigned * p = &(g_Data[0][0]);
  74. 		for (unsigned i = 0; i < gc_Rows * gc_Cols; ++i)
  75. 				sum += *p++;
  76. 	_BENCHMARK_END("   Pointer iteration (one loop)")
  77.  
  78. 	_BENCHMARK_BEGIN()
  79. 		volatile unsigned sum = 0;
  80. 		for (auto & i : g_Data)
  81. 			for (auto j : i)
  82. 				sum += j;
  83. 	_BENCHMARK_END(" Range-based for (nested loops)")
  84.  
  85. 	_BENCHMARK_BEGIN()
  86. 		volatile unsigned sum = 0;
  87. 		for (auto const & i : g_Data)
  88. 			for (auto const & j : i)
  89. 				sum += j;
  90. 	_BENCHMARK_END(" Range(const ref)(nested loops)")
  91.  
  92.  
  93. 	return 0;
  94. }
  95.  
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.cpp:4:21: fatal error: windows.h: No such file or directory
compilation terminated.
stdout
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Standard output is empty
https://ideone.com/uPPrXX
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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