std::iostream_category (3) - Linux Manuals

std::iostream_category: std::iostream_category


std::iostream_category - 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.



Return value

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


// Run this code

  #include <iostream>
  #include <fstream>

  int main()
      std::ifstream f("doesn't exist");
      try {
      } 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
failure (public member class of std::ios_base)

io_errc the IO stream error codes