Progrmming Quick Start example

In UE4 programming quick start example to make a cone goes up and down,
float RunningTime
is added to FloatingActor.h and in FloatingActor.cpp, this RunningTime is used with DeltaTime as
RunningTime += DeltaTime

How does RunningTime get initialised to zero in the .h file ? It is not explicitly put equal to zero and is not added inside AActor or its derived class constructor.

Would be appreciated if can help.

you set it to 0.f in the AFloatingActor constructor.