Re: Can't abort a loop with Print inside (V6)
- To: mathgroup at smc.vnet.net
- Subject: [mg83089] Re: Can't abort a loop with Print inside (V6)
- From: Bill Rowe <readnewsciv at sbcglobal.net>
- Date: Sat, 10 Nov 2007 03:42:15 -0500 (EST)
On 11/9/07 at 5:15 AM, frank1998 at gmail.com (Frank Hu) wrote:
>It seems in Version 6 one can't abort a loop if there's a Print
>statement inside. Try the following code
>For[i = 1, i < 1000, ++i, Print[i]]
>No matter doing it from the menu or with the keyboard shortcut, the
>abort action will be ignored. Under 5.2, the code stops right away
>when I hit Cmd-.
>Sometime, trying to abort would even freeze the whole program,
>causing lost sessions. I'm running 6.0.1.0 on Mac OS X
>10.4.10. Any suggestions of what's going on? Is this a bug or
>a new feature?
It would be better described as a feature than a bug. But the
"feature" is really nothing more than improved performance of
version 6 compared to previous versions rather than an intent to
prevent stopping a loop using Cmd-.
For any software (assuming good performance) it will be always
possible to write a loop that runs so fast that it simply cannot
be halted using the key sequence. This is a result of only
having a simple Print statement in the loop rather than having a
more complex loop.
For example, the loop
Do[Pause[1];Print[n],{n,100}]
can easily be halted with the Cmd-. key shortcut.
OTOH,
Do[Print[n],{n,100}]
cannot be halted in the same manner.
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- From: Bo Hu <bhu@cvs.rochester.edu>
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