comp.lang.idl-pvwave archive: archive » Re: IDL FOR Loop variable increments

Home » Public Forums » archive » Re: IDL FOR Loop variable increments

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: IDL FOR Loop variable increments [message #62603 is a reply to message #62602]

Fri, 19 September 2008 01:07

Carsten Lechte
Messages: 124
Registered: August 2006

Senior Member

Jean H wrote:
> Could you comment on the "risk" of changing the loop counter within the
> loop?

(You did not ask me, but I will comment anyway;)

The risk is called "obfuscation". Outside of certain competitions,
obfuscation is usually considered a thing to avoid. The first statement
in a FOR loop is a nice big billboard that clearly states: "This variable i
will consecutively hold the values from 0 to 10." Imagine your surprise
when i only iterates over some of those values, or even over some totally
different ones when you set i = -3 inside the loop body. Unless you also attach
a blinking comment that notes this unexpected behaviour, future generations
(including yourself in three months) will curse your name when they try to make
sense of your code.

Another thing to consider is if the changing of the loop variable results
in undefined behaviour. IDL seems to follow C's "anything goes" philosophy,
so it will probably work reliably. However, you are still forbidden to
change the type of the loop variable inside the loop;)

chl

Report message to a moderator

[Message index]

		Re: IDL FOR Loop variable increments By: raghuram on Mon, 22 September 2008 08:54
		Re: IDL FOR Loop variable increments By: raghuram on Sun, 21 September 2008 15:37
		Re: IDL FOR Loop variable increments By: Wasit.Weather on Sun, 21 September 2008 06:44
		Re: IDL FOR Loop variable increments By: raghuram on Fri, 19 September 2008 22:51
		Re: IDL FOR Loop variable increments By: pgrigis on Fri, 19 September 2008 12:09
		Re: IDL FOR Loop variable increments By: raghuram on Fri, 19 September 2008 12:07
		Re: IDL FOR Loop variable increments By: R.G. Stockwell on Fri, 19 September 2008 11:53
		Re: IDL FOR Loop variable increments By: MarioIncandenza on Fri, 19 September 2008 09:53
		Re: IDL FOR Loop variable increments By: pgrigis on Fri, 19 September 2008 07:26
		Re: IDL FOR Loop variable increments By: David Fanning on Fri, 19 September 2008 06:13
		Re: IDL FOR Loop variable increments By: Carsten Lechte on Fri, 19 September 2008 01:09
		Re: IDL FOR Loop variable increments By: Carsten Lechte on Fri, 19 September 2008 01:07
		Re: IDL FOR Loop variable increments By: raghuram on Thu, 18 September 2008 18:31
		Re: IDL FOR Loop variable increments By: David Fanning on Thu, 18 September 2008 15:46
		Re: IDL FOR Loop variable increments By: Jean H. on Thu, 18 September 2008 15:00
		Re: IDL FOR Loop variable increments By: Jean H. on Thu, 18 September 2008 14:52
		Re: IDL FOR Loop variable increments By: pgrigis on Thu, 18 September 2008 13:23
		Re: IDL FOR Loop variable increments By: David Fanning on Thu, 18 September 2008 13:03
		Re: IDL FOR Loop variable increments By: Jeremy Bailin on Tue, 23 September 2008 07:48

Previous Topic:	how to countor on YZ-surface
Next Topic:	Getting array indices

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 17:47:15 PDT 2025

Total time taken to generate the page: 0.00473 seconds