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Re: FOR loop ends one above where it's supposed to [message #71134 is a reply to message #71125]

Tue, 01 June 2010 22:36

cameron bowles
Messages: 5
Registered: May 2010

Junior Member

On Jun 2, 2:34 pm, cameron bowles <cameronbowle...@gmail.com> wrote:
> IDL is a little different to other languages in this regard and it
> handles for loops in this manner;
>
> 1. generates the index variable (first value, in your case i=0)
> 2. generates limit value (last value, in your case 5, stored as a
> temporary variable)
> 3. generates step value (in your case 1, stored as a temporary
> variable)
> 4. checks if limit is greater than index (for positive step values, or
> less than for negative increments), if so then FOR loop finishes.
> 5. the block of statements following the DO is executed.
> 6. the step value is added to the index
> 7. repeat steps 4->6 until step 4 fails.
>
> the difference here is IDL only uses an index variable, a lot of other
> languages uses a secondary temporary value to do the FOR conditional
> check and then updates the index only if the FOR condition is
> satisfied.
>
> hope that helps,
> Cam

I meant step 4 to read;
4. checks if index is greater than limit (for positive step values, or
less than for negative increments), if so then FOR loop finishes.

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[Message index]

		Re: FOR loop ends one above where it's supposed to By: Bulgakovv on Wed, 02 June 2010 09:49
		Re: FOR loop ends one above where it's supposed to By: penteado on Wed, 02 June 2010 09:07
		Re: FOR loop ends one above where it's supposed to By: pgrigis on Wed, 02 June 2010 08:57
		Re: FOR loop ends one above where it's supposed to By: cameron bowles on Tue, 01 June 2010 22:36
		Re: FOR loop ends one above where it's supposed to By: cameron bowles on Tue, 01 June 2010 22:34
		Re: FOR loop ends one above where it's supposed to By: mankoff on Tue, 01 June 2010 17:53

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