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  1. #include <iostream>
  2. #include <sstream>
  3. #include <vector>
  4.  
  5. // example data that imitates real file
  6. std::string example_data = R"([40, 12, 100, 3, 0.05 ,12 ,6]
  7.  
  8. [[3850.6, 1481, 592.4],
  9. [4989.4, 1919, 767.6],
  10. [3335.8, 1283, 513.2],
  11. [5142.8, 1978, 791.2],
  12. [5116.8, 1968, 787.2],
  13. [4460.3, 1715.5, 686.2],
  14. [3727.1, 1433.5, 573.4],
  15. [3248.7, 1249.5, 499.8],
  16. [4704.7, 1809.5, 723.8],
  17. [3127.8, 1203, 481.2],
  18. [3225.3, 1240.5, 496.2],
  19. [3403.4, 1309, 523.6]])";
  20.  
  21. // extractor operator to read vector from stream
  22. std::istream& operator>>(std::istream& is, std::vector<double>& vec)
  23. {
  24. 	//#1 - check if it starts from '['
  25. 	char c;
  26. 	is >> c;
  27. 	if (c != '[')
  28. 		throw std::runtime_error(std::string("Invalid character : ") + c + 
  29. 		                           " when parsing vector of double");
  30. 	//#2 - get the line till ']'
  31. 	std::string line;
  32. 	if (!std::getline(is, line, ']'))
  33. 		throw std::runtime_error("Error parsing vector of double");
  34.  
  35. 	//#3 - parse values inside '[' and ']'
  36. 	std::istringstream lstr(line);
  37. 	std::string value;
  38. 	while (std::getline(lstr, value, ','))
  39. 		vec.push_back(stod(value));
  40. 	return is;
  41. }
  42.  
  43. std::istream& operator>>(std::istream& is, std::vector<std::vector<double>>& m)
  44. {
  45. 	//#1 - check if it starts from '['
  46. 	char c;
  47. 	is >> c;
  48. 	if (c != '[')
  49. 		throw std::runtime_error(std::string("Invalid character : ") + c + 
  50. 		                           " when parsing matrix of double");
  51.  
  52.     // parse matrix line-by-line
  53.     while(true)
  54.     {
  55. 	    std::vector<double> tmp;
  56. 	    is >> tmp;
  57. 	    m.push_back(std::move(tmp));
  58. 	    // if matrix finihed, c should contain ']', else - ','
  59. 	    is >> c;
  60. 	    if (c == ']')
  61. 	    	return is;
  62. 	    if (c != ',')
  63. 			throw std::runtime_error(std::string("Invalid character : ") + c + 
  64. 			                           " when parsing matrix of double");
  65.     }
  66. }
  67. // display vector
  68. template<typename T>
  69. std::ostream& operator<<(std::ostream& os, const std::vector<T>& t)
  70. {
  71. 	os << "[";
  72. 	for (auto it = t.begin(); it != t.end(); ++it)
  73. 		os << (it != t.begin() ? ", " : "") << *it;
  74. 	os << "]";
  75. 	return os;
  76. }
  77. int main() 
  78. {
  79. 	// here you can use any std::istream
  80. 	std::istringstream in(example_data);
  81.  
  82. 	std::vector<double> vec;
  83.  
  84. 	in >> vec;
  85.  
  86. 	std::cout << "Vector: " << vec << std::endl;
  87.  
  88. 	std::vector<std::vector<double>> m;
  89. 	in >> m;
  90.  
  91. 	std::cout << "Matrix: " << m << std::endl;
  92. 	return 0;
  93. }
Success #stdin #stdout 0s 3476KB
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Standard input is empty
stdout
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Vector: [40, 12, 100, 3, 0.05, 12, 6]
Matrix: [[3850.6, 1481, 592.4], [4989.4, 1919, 767.6], [3335.8, 1283, 513.2], [5142.8, 1978, 791.2], [5116.8, 1968, 787.2], [4460.3, 1715.5, 686.2], [3727.1, 1433.5, 573.4], [3248.7, 1249.5, 499.8], [4704.7, 1809.5, 723.8], [3127.8, 1203, 481.2], [3225.3, 1240.5, 496.2], [3403.4, 1309, 523.6]]
https://ideone.com/m7icKP
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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