std::error_code(3)

NAME
std::error_code - std::error_code

Synopsis
   Defined in header <system_error>
   class error_code; (since C++11)
   std::error_code represents a platform-dependent error code value. Each
   std::error_code object holds an error code value originating from the operating
   system or some low-level interface and a pointer to an object of type
   std::error_category, which corresponds to the said interface. The error code values
   are not required to be unique across different error categories.

Member functions
   constructor constructs an error code
                        (public member function)
   operator= assigns another error code
                        (public member function)
   assign assigns another error code
                        (public member function)

Modifiers
   clear sets the error_code to value 0 in system_category
                        (public member function)

Observers
   value obtains the value of the error_code
                        (public member function)
   category obtains the error_category for this error_code
                        (public member function)
   default_error_condition obtains the error_condition for this error_code
                        (public member function)
   message obtains the explanatory string for this error_code
                        (public member function)
   operator bool checks if the value is non-zero
                        (public member function)

Non-member functions
   operator==
   operator!=
   operator< compares two error_codes
   operator<=> (function)
   (removed in C++20)
   (removed in C++20)
   (C++20)
   operator<< outputs the value and the category name to an output stream
                      (function)

Helper classes
   is_error_code_enum identifies a class as an error_code enumeration
   (C++11) (class template)
   std::hash<std::error_code> hash support for std::error_code
   (C++11) (class template specialization)

See also
   error_condition holds a portable error code
   (C++11) (class)
   error_category base class for error categories
   (C++11) (class)
   make_error_code(std::errc) creates error code value for errc enum e
   (C++11) (function)