std::is_error_code_enum<std::io_errc>

 

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is_error_code_enum<std::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

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value [static]

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operator bool	converts the object to bool, returns value (public member function)
operator() (C++14)	returns value (public member function)

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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

See also

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