FVERS

Syntax	FVERS [(#channel)] or FVERS (\file)
Location	Level-2 Device Drivers

This function reads the version number of the given file (or of the file attached to the specified channel {default #3} if the first variant is used).

The version numbers can range from 0 to 2¹⁶-1 (65535) and generally indicate how often a file has been amended. If a file was created on a level-1 device driver system, its version number is zero (0), while newly created files on level-2 device drivers will have the version number 1 after they have been closed. FVERS supports Toolkit II’s default data device and sub-directories.

If the first variant is used, the default channel is #3 if none is specified.

Each time that a file is amended on level-2 and level-3 drivers, the version number is increased by one. If the version reaches its limit of 65535, it will start at version 1 again. A file has to be re-opened to change its version by more than one. After the file has been amended, the version will only increase after a FLUSH or CLOSE.

Unfortunately current versions of SAVE and SBYTES do not increase the version number because they overwrite existing files instead of truncating them.

Example

OPEN_OVER#3,test_tmp: REMark create the file
PRINT#3,"just a line": REMark write a line to the file
PRINT FVERS(#3): REMark 0, neither flushed nor closed
CLOSE#3: REMark close file
PRINT FVERS(\test_tmp): REMark 1
OPEN#3,test_tmp: REMark re-open file
PRINT FVERS(#3): REMark 1, nothing changed yet
PRINT#3,"replace the line": REMark amend file
PRINT FVERS(#3): REMark still 1 not yet flushed
FLUSH#3: REMark write slave blocks to file
PRINT FVERS(#3): REMark now it's 2
FLUSH#3: REMark flush again
PRINT FVERS(#3): REMark  2
PRINT#3,"next line": REMark change file again
CLOSE#3: REMark close file
PRINT FVERS(\test_tmp): REMark  still 2

NOTE

The file version number is not preserved if the file is overwritten. However, if you make a copy of a file, this keeps the same version number as the original, but not on Level-1 drivers.

SMS NOTE

If you use the SAVE command without a filename to save a previously loaded SuperBASIC program, the file version number will be increased by one.

CROSS-REFERENCE

SET_FVERS allows you to set the version number.