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  1. #include <stdexcept>
  2. #include <string>
  3. #include <sstream>
  4. #include <iostream>
  5. #include <limits>
  6.  
  7. template<class T>
  8. std::wstring ToString(T input)
  9. {
  10.     std::wostringstream ss;
  11.     ss.precision(std::numeric_limits<T>::digits10);
  12.     ss << input;
  13.     if (!ss.good())
  14.     {
  15.         //Raise your favorite exception.
  16.         throw std::runtime_error("Invalid input.");
  17.     }
  18.     return std::wstring(ss.str());
  19. }
  20.  
  21. template<class T>
  22. T FromString(const wchar_t *input)
  23. {
  24.     std::wistringstream ss(input);
  25.     ss.precision(std::numeric_limits<T>::digits10);
  26.     T output;
  27.     ss >> output;
  28.     if (ss.fail() || !ss.eof())
  29.     {
  30.         //Raise your favorite exception.
  31.         throw std::runtime_error("Invalid input.");
  32.     }
  33.     return output;
  34. }
  35.  
  36. template<class T>
  37. T FromString(const std::wstring &input)
  38. {
  39.     return FromString<T>(input.c_str());
  40. }
  41.  
  42. std::wstring operator+(const wchar_t *op1, const std::wstring &op2)
  43. {
  44.     return std::wstring(op1) + op2;
  45. }
  46.  
  47. int main()
  48. {
  49.     double pi = 3.14159265359;
  50.     std::wcout.precision(std::numeric_limits<double>::digits10);
  51.     std::wcout << L"PI is " + ToString(pi) << std::endl;
  52.     const wchar_t *strPi = L"3.14159265359";
  53.     double newPi = FromString<double>(strPi);
  54.     std::wcout << newPi << std::endl;
  55.     const wchar_t *strPi2 = L"3,14159265359";
  56.     try
  57.     {
  58.         double newPi2 = FromString<double>(strPi2);
  59.         std::wcout << newPi2 << std::endl;
  60.     }
  61.     catch (std::exception &ex)
  62.     {
  63.         std::wcout << L"Exception occurred:  " << ex.what() << std::endl;
  64.     }
  65.     double newPi3 = FromString<double>(std::wstring(strPi));
  66.     std::wcout << newPi3 << std::endl;
  67.     return 0;
  68. }
  69.  
Success #stdin #stdout 0.01s 2836KB
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stdin
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Standard input is empty
stdout
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PI is 3.14159265359
3.14159265359
Exception occurred:  Invalid input.
3.14159265359
https://ideone.com/dYJMM
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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