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  1. #include <vector>
  2. #include <string>
  3. #include <memory>
  4. #include <iostream>
  5. #include <ctime>
  6. #include <cstdlib>
  7.  
  8. #define LEN 1000000
  9.  
  10. char stringlengths[LEN];
  11.  
  12. int main(void)
  13. {
  14. 	srand(0);
  15. 	int totalalloc = 0;
  16. 	for(int i=0; i<LEN; ++i) {
  17. 		stringlengths[i] = rand()%16;
  18. 		totalalloc += stringlengths[i];
  19. 	}
  20. 	std::cout << "total string length to be allocated: " << totalalloc << '\n';
  21. 	int pre, post;
  22. #if 0
  23. 	{
  24. 		std::cout << "virtual memory before: ";
  25. 		std::cin >> pre;
  26. 		std::unique_ptr<char*[]> ctest(new char*[LEN]);
  27. 		for(int i=0; i<LEN; ++i)
  28. 			ctest[i] = new char[stringlengths[i]];
  29. 		std::cout << "virtual memory after: ";
  30. 		std::cin >> post;
  31. 		std::cout << "char* difference of " << (post-pre) << '\n';
  32. 		for(int i=0; i<LEN; ++i)
  33. 			delete [] ctest[i];
  34. 	}
  35. #endif
  36. #if 0
  37. 	{
  38. 		std::cout << "virtual memory before: ";
  39. 		std::cin >> pre;
  40. 		std::unique_ptr<std::unique_ptr<char[]>[]> ctest(new std::unique_ptr<char[]>[LEN]);
  41. 		for(int i=0; i<LEN; ++i)
  42. 			ctest[i].reset(new char[stringlengths[i]]);
  43. 		std::cout << "virtual memory after: ";
  44. 		std::cin >> post;
  45. 		std::cout << "unique_ptr difference of " << (post-pre) << '\n';
  46. 	}
  47. #endif
  48. #if 1
  49. 	{
  50. 		std::cout << "virtual memory before: ";
  51. 		std::cin >> pre;
  52. 		std::unique_ptr<std::string[]> ctest(new std::string[LEN]);
  53. 		for(int i=0; i<LEN; ++i)
  54. 			ctest[i].resize(stringlengths[i]);
  55. 		std::cout << "virtual memory after: ";
  56. 		std::cin >> post;
  57. 		std::cout << "std::string difference of " << (post-pre) << '\n';
  58. 	}
  59. #endif
  60. 	std::cin >> pre;
  61.     return 0;
  62. }
Success #stdin #stdout 0.26s 29816KB
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Standard input is empty
stdout
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total string length to be allocated: 7499235
virtual memory before: virtual memory after: std::string difference of -143117476
https://ideone.com/ynJhF
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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