Oracle C++ Call Interface Programmer's Guide

IntervalDS Class
Constructs an IntervalDS object as a copy of an Interval reference.
IntervalDS(const Interval &src);
The following code example demonstrates that the default constructor creates a null
value, and how you can assign a non null value to a day-second interval and then
perform operations on it:
Environment *env = Environment::createEnvironment();
//create a null day-second interval
IntervalDS ds;
if(ds.isnull())
cout