TRUNCATE

Syntax

TRUNCATE #channel [\position] or

TRUNCATE

Location Toolkit II, THOR XVI

Every file has a certain length, measured in bytes, which can be reduced with the command TRUNCATE. If TRUNCATE is used without the position parameter, the end of the file will be moved to the current file pointer position, meaning that for most purposes, the last byte of the file is the byte which was being pointed to.

If you supply a second parameter, then the file pointer is set to the given position before the file is TRUNCATEd. Note that any data after the new ‘end of file’ will be lost.

TRUNCATE returns error -15 (invalid parameter) if the specified channel is not actually linked to a file. A position greater than the actual file length, such as position>=FLEN(#channel) has no effect. TRUNCATE without any parameters uses #3 as the default channel and is therefore the same as:

TRUNCATE #3

NOTE

The syntax TRUNCATE \position is not valid, error -17 (error in expression) will be reported. You have to specify a channel number if you intend to set the file pointer before truncating the file.

CROSS-REFERENCE

FLEN and FILE_LEN return the length of a file, FPOS and FILE_POS the current file pointer position, FILE_PTRA and FILE_PTRR move the file pointer as do GET, PUT, BGET and BPUT.