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Re: How to Break[] out of nested loops?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg21937] Re: How to Break[] out of nested loops?
  • From: pecora at zoltar.nrl.navy.mil (Lou Pecora)
  • Date: Sat, 5 Feb 2000 00:49:14 -0500 (EST)
  • Organization: Naval Research Lab
  • References: <86r7bm$b72@smc.vnet.net> <870vkl$8ni@smc.vnet.net> <87duti$2jv$5@dragonfly.wolfram.com>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <87duti$2jv$5 at dragonfly.wolfram.com>, Ed McBride
<emcbride at wybron.com> wrote:

> > Julian:
> > 
> > Suggestion: use Throw and Catch:
> > 
> > x = 0;
> > Do[x = m^2;
> >     Do[If[2n + x > 30, Throw[Null]], {n, 5}], {m, 7}] // Catch
> > 
> > Allan
> > ---------------------
> 
> Or, if you happen to be an organized, disciplined person who does not
> rank go-to-type statements right up there with sacrilege, you could even
> stoop to a "Goto" statement.  I mean, if God didn't want us to use this
> statement, why would Mr. Wolfram have been 
> permitted to include it in his software package?
> Ed McBride, P.E.

I have to agree with this.  Sometimes efforts to break from nested loops
can become complicated, even arcane (e.g. above, using exceptions to break
form loops? -- no offense intended).  When you want to just get out of
something a clear Goto a label works fine.  Same in C.

Lou Pecora,  email:  pecora at anvil.nrl.navy.mil
Naval Research Laboratory, Washington, D.C. 20375-5000, U.S.A.
 == My comments are my own and do not reflect the views of the U.S. Navy. ==
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