dnrec - return number of allocated records
long dnrec (fcb)
Dnrec returns the number of records allocated to an opened
RMSfile. For "hashed" RMSfiles, this is the number of records
specified when you last created or expanded the RMSfile. For
non-hashed RMSfiles, dnrec returns the total number of deleted
and active records currently in the RMSfile.
Fcb is the file block pointer returned by dlopen(C-3) or
Chapter 4, RMS Programming Guide
C/Base Reference Manual Chapter 4, "Creating RMSfiles"
Dnrec returns a value of BAD (-1) if fcb is not an opened file