Determines the size of a file, in bytes
(vl-file-size filename)
If successful, vl-file-size returns an integer showing the size of filename. If the file is not readable, vl-file-size returns nil. If filename is a directory or an empty file, vl-file-size returns 0.
(vl-file-size "c:/autoexec.bat") 1417 (vl-file-size "c:/") 0
In the preceding example, vl-file-size returned 0 because c:/ names a directory.