Opens a file for access by the AutoLISP I/O functions
(open filename mode)
open assumes you are referring to the AutoCAD default drawing directory.A string that specifies the name and extension of the file to be opened. If you do not specify the full path name of the file,
Indicates whether the file is open for reading, writing, or appending. Specify a string containing one of the following letters:
râ€ƒOpen for reading.
close function.wâ€ƒOpen for writing. If filename does not exist, a new file is created and opened. If filename already exists, its existing data is overwritten. Data passed to an open file is not actually written until the file is closed with the
aâ€ƒOpen for appending. If filename does not exist, a new file is created and opened. If filename already exists, it is opened and the pointer is positioned at the end of the existing data, so new data you write to the file is appended to the existing data.
The mode argument can be uppercase or lowercase. Note that in releases prior to AutoCAD 2000, mode had to be specified in lowercase.
open returns a file descriptor that can be used by the other I/O functions. If mode "r" is specified and filename does not exist, open returns nil.If successful,
Open an existing file:
Command: (setq a (open "c:/program files/ <AutoCAD installation directory>/help/filelist.txt" "r"))
#<file "c:/program files/ <AutoCAD installation directory>/help/filelist.txt">
open against files that do not exist:The following examples issue
Command: (setq f (open "c:\\my documents\\new.tst" "w"))
#<file "c:\\my documents\\new.tst">
Command: (setq f (open "nosuch.fil" "r"))
Command: (setq f (open "logfile" "a"))