Re: BINARY FILES

[mole6e23(at)hotmail.com (Todd Clements)]

mohamed_nur@my-deja.com wrote:

>I've been dealing with binary files and every case i had to know before
>hand the dimensions of the array to setup an IDL variable of the said
>dimesions and read the unformatted data into.
>
>But is it possible or is there a method (in IDL 5.2/5.3) to read it in
>with no knowledge of the dimensions of the array.


I always use the fstat routine, which gets a bunch of information about
the file, but the only one I ever use is the size field:

;-----
openr,lun,'file.dat',/get_lun
stat = fstat( lun )

array = fltarr( stat.size )

readu,lun,array

free_lun, lun
;----

Alternatively, if you're on UNIX, you can use the /nostdio keyword which
lets you just read willy nilly until the end of the file, and then get the
transfer count from the readu procedure. It's not a good way of doing
things, in my opinion, but it works:

;; Allocate a much bigger array than you need
array = fltarr( 1e5 )
openr,lun,'file.dat',/get_lun,/nostdio
readu,lun,array,transfer_count=count
array = temporary(array)[0:count-1]
free_lun, lun


Hope this helps,
Todd