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std::iostream_category

Defined in header <ios> 
const std::error_category& iostream_category() noexcept;
 (since C++11)

Obtains a reference to the static error category object for iostream errors. The object is required to override the virtual function error_category::name() to return a pointer to the string "iostream". It is used to identify error codes provided in the exceptions of type std::ios_base::failure.

Parameters

(none).

Return value

A reference to the static object of unspecified runtime type, derived from std::error_category.

Example

#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"
                  << "Error code: " << e.code().value() 
                  << " (" << e.code().message() << ")\n"
                  << "Error category: " << e.code().category().name() << '\n';
 
    }
}

Possible output:

Caught an ios_base::failure.
Error code: 1 (unspecified iostream_category error)
Error category: iostream

See also

stream exception
(public member class of std::ios_base)
(C++11)
 the IO stream error codes
(enum)

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