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Re: BINARY FILES [message #21975]

Fri, 13 October 2000 00:00

mole6e23
Messages: 31
Registered: December 1998

Member

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

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		Re: BINARY FILES By: mole6e23 on Fri, 13 October 2000 00:00
		Re: BINARY FILES By: davidf on Fri, 13 October 2000 00:00

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