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Re: Unsigned Integers - How? [message #8121 is a reply to message #8115]

Fri, 07 February 1997 00:00

David Foster
Messages: 341
Registered: January 1996

Senior Member

David Fanning wrote:
>
> Peter Berdeklis <peter@atmosp.physics.utoronto.ca> writes:
>
>> I'm trying to read a binary data file into IDL. Included in the data
>> headers are several unsigned integers for dates and times. Some of the
>> unsinged integers are overflowing, giving me negative integers. How do I
>> specify a variable as an unsinged integer in IDL?
>
> It's deja vu all over again, as one of our famous baseball players once
> said. :-)
>
> Read the unsinged integers into *signed* 16-bit integers in IDL.
> (You are already doing this, apparently).
>
> date = 0L
> time = 0L
> READU, lun, datafile, date, time
>
> Convert them to the correct *unsigned* values, like this:
>
> date = LONG(date) AND 'FFFF'x
> time = LONG(time) AND 'FFFF'x
>

Oops! If you specify LONG then you get 32-bit integers. So:

date = fix(0)
time = fix(0)
readu, lun, datafile, date, time

date = date AND 'FFFF'x
time = time AND 'FFFF'x

Of course, if you want 32-bit integers, use LONG like Dave suggested.

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 2200
La Jolla, CA 92037
[ UCSD Mail Code 0949 ]
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[Message index]

		Re: Unsigned Integers - How? By: Peter Berdeklis on Fri, 07 February 1997 00:00
		Re: Unsigned Integers - How? By: davidf on Fri, 07 February 1997 00:00
		Re: Unsigned Integers - How? By: David Foster on Fri, 07 February 1997 00:00
		Re: Unsigned Integers - How? By: David Foster on Fri, 07 February 1997 00:00
		Re: Unsigned Integers - How? By: davidf on Fri, 07 February 1997 00:00

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