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  1. #include <iostream>
  2. using namespace std;
  3. #include <system_error>
  4. #include <cassert>
  5.  
  6. namespace mylib
  7. {
  8.     namespace errc {
  9.  
  10.         enum my_error
  11.         {
  12.             failed = 0
  13.         };
  14.  
  15.         inline const char* error_message(int c)
  16.         {
  17.             static const char* err_msg[] = 
  18.             {
  19.                 "Failed",
  20.             };
  21.  
  22.             assert(c < sizeof(err_msg) / sizeof(err_msg[0]));
  23.             return err_msg[c];
  24.         }
  25.  
  26.         class my_error_category : public std::error_category
  27.         {
  28.             public:
  29.  
  30.             my_error_category()
  31.             { }
  32.  
  33.             std::string message(int c) const
  34.             { 
  35.                 return error_message(c); 
  36.             }
  37.  
  38.             const char* name() const { return "My Error Category"; }
  39.  
  40.             const static error_category& get()
  41.             {
  42.                 const static my_error_category category_const;
  43.                 return category_const;
  44.             }
  45.         };
  46.  
  47. 	inline std::error_code make_error_code(my_error e)
  48. 	{
  49.     		return std::error_code(static_cast<int>(e), my_error_category::get());
  50. 	}
  51.  
  52.     } // end namespace errc
  53. } // end namespace mylib
  54.  
  55. namespace std {
  56.  
  57. template<>
  58. struct is_error_code_enum<mylib::errc::my_error>
  59.     : std::true_type
  60. { }; 
  61.  
  62. } // end namespace std
  63.  
  64. int main()
  65. {
  66.     std::error_code ec1 = mylib::errc::make_error_code(mylib::errc::failed); // works
  67.     std::error_code ec2 = mylib::errc::failed; // works
  68.     bool result = (ec2 == mylib::errc::failed); // works
  69.  
  70.     std::cout << ec1 << std::endl;
  71. }
Success #stdin #stdout 0s 2932KB
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Standard input is empty
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My Error Category:0
https://ideone.com/eSfee
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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