std::error_code::category
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                    < cpp | error | error code
                    
                                                            
                    |   const std::error_category& category() const noexcept;  | 
(since C++11) | |
Returns the error category of the error value.
Parameters
(none)
Return value
The error category of the error value.
See also
|    obtains the value of the error_code  (public member function)  |