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  1. #include <iostream>
  2. #include <string>
  3. #include <cstdlib>
  4. #include <cmath>
  5.  
  6. using namespace std;
  7. long long stringToLongLong(string myString, unsigned short base = 10)
  8. {
  9. 	std::string::iterator beginningOfNumber = myString.begin(), 
  10. 		pointerToWhereYouLeftItLastTime = myString.begin();
  11.  
  12. 	long long returnValue = 0;	
  13.  
  14. 	if (base >= 2 || base <= 10)
  15. 	{
  16. 		while (pointerToWhereYouLeftItLastTime != myString.end() && (*pointerToWhereYouLeftItLastTime < 48 || *pointerToWhereYouLeftItLastTime > 48 + base - 1))
  17. 		{
  18. 			pointerToWhereYouLeftItLastTime++;
  19. 		}
  20.  
  21. 		if (pointerToWhereYouLeftItLastTime != myString.end())
  22. 		{
  23. 			beginningOfNumber = pointerToWhereYouLeftItLastTime;
  24. 		}
  25. 		while (pointerToWhereYouLeftItLastTime != myString.end() && *pointerToWhereYouLeftItLastTime >= 48 && *pointerToWhereYouLeftItLastTime <= 48 + base - 1)
  26. 		{
  27. 			pointerToWhereYouLeftItLastTime++;
  28. 		}
  29. 	}
  30. 	else if (base <= 16)
  31. 	{
  32. 		while (pointerToWhereYouLeftItLastTime != myString.end() && (*pointerToWhereYouLeftItLastTime < 48 || *pointerToWhereYouLeftItLastTime > 57) && (*pointerToWhereYouLeftItLastTime < 65 || *pointerToWhereYouLeftItLastTime > 65 + base - 11) && (*pointerToWhereYouLeftItLastTime < 97 || *pointerToWhereYouLeftItLastTime > 97 + base - 11))
  33. 		{
  34. 			pointerToWhereYouLeftItLastTime++;
  35. 		}
  36.  
  37. 		if (pointerToWhereYouLeftItLastTime != myString.end())
  38. 		{
  39. 			beginningOfNumber = pointerToWhereYouLeftItLastTime;
  40. 		}
  41. 		while (pointerToWhereYouLeftItLastTime != myString.end() && (*pointerToWhereYouLeftItLastTime >= 48 && *pointerToWhereYouLeftItLastTime <= 57 || *pointerToWhereYouLeftItLastTime >= 65 && *pointerToWhereYouLeftItLastTime <= 65 + base - 11 || *pointerToWhereYouLeftItLastTime >= 97 && *pointerToWhereYouLeftItLastTime <= 97 + base - 11))
  42. 		{
  43. 			pointerToWhereYouLeftItLastTime++;
  44. 		}
  45. 	}
  46.  
  47. 	if (beginningOfNumber < myString.end())
  48. 	{
  49. 		for (unsigned long long lenght = pointerToWhereYouLeftItLastTime - beginningOfNumber; lenght > 0; lenght--)
  50. 		{
  51. 			returnValue += (*beginningOfNumber - '0')*std::pow(base,  (lenght - 1));
  52.  
  53. 			beginningOfNumber++;
  54. 		}
  55. 	}
  56.  
  57. 	return returnValue;
  58. }
  59.  
  60. int main()
  61. {
  62. 	string s = "1000";
  63. 	long long l = stringToLongLong(s);
  64. 	std::cout << l << std::endl;
  65. }
Success #stdin #stdout 0s 3472KB
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1000
https://ideone.com/dw8YXU
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
secret

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