| Re: IDL FOR Loop variable increments [message #62583 is a reply to message #62580] |
Fri, 19 September 2008 22:51   |
raghuram
Messages: 32
Registered: February 2008
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Member |
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On Sep 19, 12:09 pm, pgri...@gmail.com wrote:
> R.G. Stockwell wrote:
>> "Jean H" <jghas...@DELTHIS.ucalgary.ANDTHIS.ca> wrote in message
>> news:gauiil$u32$1@news.ucalgary.ca...
>> ...
>>> Could you comment on the "risk" of changing the loop counter within the
>>> loop?
>
>> my 2 cents.
>
>> First, it is in changing the counter of a for loop.
>> A for loop explicitly outlines what all counter variables will be.
>
>> There are two things:
>
>> 1) infinite loop, one could easily change the counter to never
>> reach the end condition. A (valid) for loop will always reach the end
>> condition.
>
>> 2) more insidious, you could inadvertantly cast the counter to a float from
>> an int, and then have one extra (and unintended ) statement executed.
>
> This seems not to be possible in IDL, as loop counters, unlike normal
> variables, cannot change their type.
>
> Ciao,
> Paolo
>
>
>
>> instead of 0,1,2,3,4,5,6 (and not executing i = 7) you could get
>> 0,1,2,3,4,4.99999999,5.99999,6.99999999, (and effectively executing the
>> extra i ~ 7 step).
>
>> Cheers,
>> bob
Hi all,
Thanks for your replies. Just as David mentioned in his first
response, a while loop worked out much better. Within a single while
loop, i was able to accomplish the task, albeit a bit slowly because
of the non-array operation.
Thanks !
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