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Re: How to change the increment of FOR loop? [message #65603 is a reply to message #65602]

Wed, 11 March 2009 14:24

Foldy Lajos
Messages: 268
Registered: October 2001

Senior Member

On Wed, 11 Mar 2009, Hu wrote:

> Hi, there
> I got a question relating to the variational increment of FOR
> Statement. I used the code like this:
> ;;; begin
> increment =20
> FOR j = 0, N-1, increment DO BEGIN
> IF a gt 0 THEN BEGIN
> ;......
> increment=10
> ENDIF ELSE BEGIN
> ;......
> increment=12
> ENDELSE
> ENDFOR
> ;; end
>
> But the increment have not changed according to IF... ELSE ...
> statement..
> What I want is to change the increment according to different
> conditions. that is, if variable a is greater than 0, the increment of
> the FOR loop will be 10 , not its default value 20.....
>
> Is there any solution to this problem?

increment is evaluated only once, before the loop starts (and it is copied
to a temporary variable you can not reach). You have to create a loop
manually:

j=0
increment=20
while 1 do begin

IF a gt 0 THEN BEGIN
;......
increment=10
ENDIF ELSE BEGIN
;......
increment=12
ENDELSE

j=j+increment
if j ge n then break

endwhile

regards,
lajos

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[Message index]

		Re: How to change the increment of FOR loop? By: Allan Whiteford on Thu, 12 March 2009 05:24
		Re: How to change the increment of FOR loop? By: Hu on Wed, 11 March 2009 14:42
		Re: How to change the increment of FOR loop? By: Foldy Lajos on Wed, 11 March 2009 14:24
		Re: How to change the increment of FOR loop? By: Foldy Lajos on Fri, 13 March 2009 03:31

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