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std::is_error_code_enum<std::io_errc>

From cppreference.com
< cpp‎ | io‎ | io errc
Defined in header <ios>
template< >
struct is_error_code_enum<std::io_errc> : public std::true_type { };
(since C++11)

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.

Contents

Inherited from std::integral_constant

Member constants

value
[static]
true
(public static member constant)

Member functions

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

Member types

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

[edit] Example

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

#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

[edit] See also

identifies a class as an error_code enumeration
(class template) [edit]
holds a platform-dependent error code
(class) [edit]
(C++11)
the IO stream error codes
(enum) [edit]