| Defined in header <system_error> | ||
|---|---|---|
const std::error_category& system_category(); | (since C++11) |
Obtains a reference to the static error category object for errors reported by the operating system. The object is required to override the virtual function std::error_category::name() to return a pointer to the string "system". It is also required to override the virtual function std::error_category::default_error_condition() to map the error codes that match POSIX errno values to std::generic_category.
Parameters
(none).
Return value
A reference to the static object of unspecified runtime type, derived from std::error_category.
Exceptions
noexcept specification: noexceptExample
#include <iostream>
#include <system_error>
#include <iomanip>
#include <string>
int main()
{
std::error_condition econd = std::system_category().default_error_condition(EDOM);
std::cout << "Category: " << econd.category().name() << '\n'
<< "Value: " << econd.value() << '\n'
<< "Message: " << econd.message() << '\n';
econd = std::system_category().default_error_condition(10001);
std::cout << "Category: " << econd.category().name() << '\n'
<< "Value: " << econd.value() << '\n'
<< "Message: " << econd.message() << '\n';
}Output:
Category: generic Value: 33 Message: Numerical argument out of domain Category: system Value: 10001 Message: Unknown error 10001
See also
| (C++11) | identifies the generic error category (function) |
| (C++11) | the std::error_condition enumeration listing all standard <cerrno> macro constants (class) |
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