std::is_error_code_enum<std::io_errc> - cppreference.com

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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.

## 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)
operator() (C++14) | 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

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

### [edit] See also

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

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