| Re: IDL FOR Loop variable increments [message #62593 is a reply to message #62592] |
Fri, 19 September 2008 11:53   |
R.G. Stockwell
Messages: 363
Registered: July 1999
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Senior Member |
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"Jean H" <jghasban@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.
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
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