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Re: Please help me avoid loops and conditionals [message #36410 is a reply to message #36332]

Wed, 10 September 2003 10:06

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Patrick Ford writes:

> The second is related to the same program. I want to take a string of
> 4 contiguous bytes and convert them into a long unsigned or signed
> integer. I remember doing this in Fortran, Pascal and C with some
> variations on a theme of having variables of type byte and long point
> to the same memory location. Is there some clever way of doing the
> same in IDL? My current klugy method is based on the following:
>
> R = ary(p) + (16 * ary(p+1)) + (16^2 * ary(p+2)) + (16^3 * ary(p+3))
>
> Where ary is a byte array.

This is what the LONG and ULONG functions are used for.
The first positional parameter is the byte array you want
to read from and the second positional parameter is
the offset into the array.

number = Long(ary, 16) ; skip first 16 bytes, read next four.

Cheers,

David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		Please help me avoid loops and conditionals By: pford on Tue, 09 September 2003 09:44
		Re: Please help me avoid loops and conditionals By: pford on Sat, 13 September 2003 13:58
		Re: Please help me avoid loops and conditionals By: Chris Lee on Fri, 19 September 2003 02:40
		Re: Please help me avoid loops and conditionals By: David Fanning on Wed, 10 September 2003 10:06
		Re: Please help me avoid loops and conditionals By: Chris Lee on Wed, 10 September 2003 07:15

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