std::is_error_code_enum<std::io_errc> (3) - Linux Manuals

std::is_error_code_enum<std::io_errc>: std::is_error_code_enum<std::io_errc>

NAME

std::is_error_code_enum<std::io_errc> - std::is_error_code_enum<std::io_errc>

Synopsis

Defined in header <ios>
template< > (since C++11)
struct is_error_code_enum<std::io_errc> : public std::true_type { };

This specialization of std::is_error_code_enum informs other library components that values of type std::io_errc are enumerations that hold error codes, which makes them implicitly convertible and assignable to objects of type std::error_code.

Inherited from std::integral_constant

Member constants

value true
         (public static member constant)
[static]

Member functions

              converts the object to bool, returns value
operator bool (public member function)

operator() returns value
              (public member function)
(C++14)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Example

The comparison between e.code() and std::io_errc::stream compiles because std::is_error_code_enum<std::io_errc>::value == true
// Run this code

  #include <iostream>
  #include <fstream>
  int main()
  {
      std::ifstream f("doesn't exist");
      try {
          f.exceptions(f.failbit);
      } catch (const std::ios_base::failure& e) {
          std::cout << "Caught an ios_base::failure.\n";
          if(e.code() == std::io_errc::stream)
              std::cout << "The error code is std::io_errc::stream\n";
      }
  }

Output:

  Caught an ios_base::failure.
  The error code is std::io_errc::stream