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  1. #include <chrono>
  2. #include <iostream>
  3. #include <cstdlib>
  4. #include <cstring>
  5. using namespace std;
  6. using namespace chrono;
  7.  
  8. int testcases[0xffff];
  9.  
  10. void prepare_testcases()
  11. {
  12. 	for(size_t i = 0; i < sizeof(testcases); i++)
  13. 	{
  14. 		testcases[i] = rand();
  15. 	}
  16. }
  17.  
  18. inline int cmp_normal(int i, int j)
  19. {
  20. 	return i == j;
  21. }
  22.  
  23. inline int cmp_mem(int i, int j)
  24. {
  25. 	return memcpy(&i, &j, sizeof(int)) == 0;
  26. }
  27.  
  28. high_resolution_clock::duration test(int(cmpfunc)(int, int))
  29. {
  30.   auto tbegin = high_resolution_clock::now();
  31.   volatile int sink;
  32.   for(size_t i = 1; i < sizeof(testcases); i++)
  33.   	sink = cmpfunc(testcases[i], testcases[i-1]);
  34.   auto tend = high_resolution_clock::now();
  35.   return tend - tbegin;
  36. }
  37.  
  38. int main()
  39. {
  40.   prepare_testcases();
  41.  
  42.   cout << "Normal comparison took " << duration_cast<milliseconds>(test(cmp_normal)).count() << " milliseconds." << endl;
  43.   cout << "Memory comparison took " << duration_cast<milliseconds>(test(cmp_mem)).count() << " milliseconds." << endl;
  44. }
Runtime error #stdin #stdout 0s 16304KB
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https://ideone.com/5zpRct
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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