How to check if std::hex is set

[eklavya sharma 2]

I have made a class named luint for handling very large unsigned integers. I want to overload the input and output operators std::ostream& operator<<(std::ostream&,const luint&) and
std::istream& operator>>(std::istream&,luint&).

I want to write such an implementation that if std::hex is set, my program displays the large integer in hexadecimal form instead of decimal form. How can I do this?

[Peter87]

if (stream.flags() & std::ios::hex)
{
	// "std::hex is set"
}