| Re: Converting Byte Arrays [message #10046 is a reply to message #10032] |
Mon, 06 October 1997 00:00   |
David Foster
Messages: 341
Registered: January 1996
|
Senior Member |
|
|
Thomas Price wrote:
>
> I am struggling with a file i/o problem. I have a data file which comes
> from a PC. I know the data structure in terms of how many bytes correspond
> to each entry in the file and what file type for each of these entries
> (i.e. integer, real, etc). Generally, I two bytes into a variable for a
> integer and 4 bytes for a real. I can convert the integers simply enough.
> For a variable named id which is a bytarr(2) the integer is simply
> 256*id(1)+id(0). However, how can I convert the 4 byte arrays which are
> floats into the proper numbers? I seem to come up with gibberish if I do a
> simple float(val) where val=byytarr(4).
>
> Any thoughts or tricks? All help much appreciated.
Remember that the byte-ordering on Suns and PCs is reversed. I think
the easiest and most efficient thing to do would be to read the
data into variables directly, using the appropriate data-type,
and then convert them using the BYTEORDER() routine.
If you are going to convert short integers by hand then I think
you might need:
256*id[0]+id[1]
to account for the reversed byte ordering.
Dave
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
David S. Foster Univ. of California, San Diego
Programmer/Analyst Brain Image Analysis Laboratory
foster@bial1.ucsd.edu Department of Psychiatry
(619) 622-5892 8950 Via La Jolla Drive, Suite 2240
La Jolla, CA 92037
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
