The BVolumeRoster class keeps track of the volumes that are mounted in the file system hierarchy. It lets you know about volumes in two ways:

• It lists the volumes that are currently mounted. You can step through the list through iterative calls to the GetNextVolume() function.

• It lets you know when new volumes are mounted, and when existing volumes are unmounted. (See StartWatching().)

How you create your BVolumeRoster object depends on what you're going to do with it:

• If you simply want to step through the volume list, then creating a BVolumeRoster on the stack is sufficient.

• However, if you want to watch for volumes being mounted and unmounted, then you must keep your BVolumeRoster object around. The watching stops when the object is deleted.

A single BVolumeRoster object can perform both functions: You can use it to step through the volume list at the same time that it's watching volumes.