{

// OS-specific error code

boost::system::error_code errorCode;

// Open the file using the Windows or the POSIX API.

// Note that we try to open a file in a subdirectory that doesn't exist because

// that will cause Windows to return a different error code than when the directory

// exists but not the file. If we didn't do that both type of calls would return 2.

#ifdef _WIN32

HANDLE file = CreateFile(L"doesnotexist/doesnotexist", GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);

DWORD lastError = GetLastError();

if (file == INVALID_HANDLE_VALUE)

{

std::cout << "Failed to open file. GetLastError(): " << lastError << std::endl;

}

errorCode = boost::system::error_code(lastError, boost::system::system_category());

#else

int file = open("doesnotexist/doesnotexist", O_RDONLY);

if (file == -1)

{

std::cout << "Failed to open file. errno: " << errno << std::endl;

}

errorCode = boost::system::error_code(errno, boost::system::system_category());

#endif

// Output the OS-specific error code

std::cout << "error_code: " << errorCode << std::endl;

// Convert the OS-specific error code into a generic error_condition

// error_condition doesn't implement << the same way error_code does so we format it explicitly

boost::system::error_condition errorCondition = errorCode.default_error_condition();

std::cout << "error_condition: " << errorCondition.category().name() << ":" << errorCondition.value() << std::endl;

return 0;