[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Hex constants interpreted differently in IDL/v5.2

William Thompson (thompson@orpheus.nascom.nasa.gov) writes:

> Apparently, IDL/v5.2 interprets some hexadecimal constants differently than
> previous versions.  For example, the statement
> 	IDL> help,'aa7f'x
> under IDL/v5.1 produces the result
> 	<Expression>    LONG      =        43647
> while under IDL/v5.2, the following is returned
> 	<Expression>    INT       =   -21889

Yep. I think I reported this already. (Or meant to,
if I didn't.)

I first noticed it with this kind of syntax:

   Plot, data, Color='00ffff'x

This used to draw a yellow plot, but started drawing
white plots in IDL 5.2. Of course, the previous behavior
was decidedly a bug (that I had gotten used to, darn it),
but if you want a 24-bit number, you really do need to 
make it a long:

   Plot, data, color='00ffff'xL

I presume the bug was found and fixed when the programmers
were implementing the unsigned integer data type. :-)


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