LOF function

Purpose | Return the length of an open disk file.
Syntax | y&& = LOF([#] filenum&)
Remarks | filenum& is the file number with which the file was opened. LOF returns the size of the indicated file in bytes, in the Quad-integer range 0 to 2^63-1. The Number symbol (#) is optional, but recommended for clarity.
See also | FILEATTR, LOC, SEEK function, SEEK statement
Example | OPEN "RECIPES.DAT" FOR BINARY AS #1 x&& = LOF(1) CLOSE #1