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Re: endless loops suck [message #33823 is a reply to message #33820]

Mon, 03 February 2003 15:36

Pete[2]
Messages: 3
Registered: February 2003

Junior Member

Hi,
I've come across this problem before when updating plots.

This will not not break:

PRO doomed_to_continue
a=0L
While (1) DO BEGIN
a=a+1
ENDWHILE
END

This will break:

PRO happy_to_break
a=0L
While (1) DO BEGIN
a=a+1
wait,0.0001
ENDWHILE
END

as will this:

PRO happy_to_break_2
a=0L
While (1) DO BEGIN
a=a+1
print,''
ENDWHILE
END

At times, I've had to put in a wait statement after a plot statement to make
it display, if the plot statement is in a loop and if there is no other way
to interrupt the excecution of the loop. Weird!

Peter

"Thomas Gutzler" <tgutzler@ee.uwa.edu.au> wrote in message
news:3E3DDF77.3040908@ee.uwa.edu.au...
> good morning,
>
> David Fanning wrote:
>>
>> So I admit, "infinite" WHILE loops *can* be interrupted, as long as
>> they use BEGIN ... END statement blocks. Try this:
>>
>> PRO Test
>> While 1 DO BEGIN
>> Print, 'Test before you Post!'
>> ENDWHILE
>> END
>
> I thought about this and figured out that I have a loop with begin
> and end. It looks like that:
>
> PRO SnakeInterp,xi,yi,dmax,dmin
> ; x,y are arrays of coordinates
> ; dmin, dmax are preferred min and max distance between coordinates
> [...]
> ; WHILE (MAX(d) GT dmax) DO BEGIN ; this would be correct
> WHILE (1) DO BEGIN ; this obviously loops to dead
> idx0 = (d GT dmax)
> => z = SnakeIndex(idx0) ; debugger is here
> p = INDGEN(N+1)+1
> xi = InterPol([xi,xi[0]],p,z)
> yi = InterPol([yi,yi[0]],p,z)
> N = N_ELEMENTS(xi)
> d = abs( [xi[1:N-1],xi[0]] - xi) + abs( [yi[1:N-1],yi[0]] - yi)
> ENDWHILE
> END
>
> FUNCTION snakeindex, idx
> ; SNAKEINDEX Create index for adpative interpolating the snake
> arr = idx
> N = N_ELEMENTS(xi)
> arr = (TRANSPOSE([[arr],[INTARR(N)+1]]))[0:2*N-2]
> y = DOUBLE(WHERE([1,arr] EQ 1))/2+1
> RETURN, y
> END
>
> I pressed "Step out", then CTRL+BREAK (10 times) then CTRL+c (another 10
> times) then I made myself a tea and read some news. After half an hour
> taskmanager was my friend again :(
> I thought maybe the compiler needs a little bit of time to finish
> currently running processes before it polls the keyboard again and breaks.
>
>> On my Windows machine I can interrupt this program (after I've
>> learned my lesson) by doing a CNTL-Break.
>
> I could interrupt the Print, 'Test before you Post!' loop with this, yes.
>
> Perhaps I just should pay more attention to my sourcecode.
>
> Tom
>

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[Message index]

		Re: endless loops suck By: Thomas Gutzler on Mon, 03 February 2003 17:57
		Re: endless loops suck By: Pete[2] on Mon, 03 February 2003 15:36
		Re: endless loops suck By: Thomas Gutzler on Sun, 02 February 2003 19:18
		Re: endless loops suck By: David Fanning on Sat, 01 February 2003 08:14
		Re: endless loops suck By: David Fanning on Fri, 31 January 2003 11:38
		Re: endless loops suck By: Pavel A. Romashkin on Fri, 31 January 2003 11:11
		Re: endless loops suck By: Timm Weitkamp on Fri, 31 January 2003 05:02
		Re: endless loops suck By: thompson on Tue, 04 February 2003 09:11
		Re: endless loops suck By: thompson on Tue, 04 February 2003 09:13
		Re: endless loops suck By: Timm Weitkamp on Tue, 04 February 2003 01:14

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