[R] how does while work

[Giovanni Petris]

Maybe warning() or stop() can be used for this purpose.

Giovanni

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> What he wanted is a mechanism to "watch" for a condition on a variable, and
> stop execution as soon as that condition is TRUE, regardless of where in the
> program.  The only thing that I know of that sort of does this is inside
> gdb, the GNU debugger.  AFAIK this is impossible.  If anyone has better
> idea, I'd like to hear about it, too.
> 
> Andy
> 
> > -----Original Message-----
> > From: David A Richmond [mailto:richmond at saintmarys.edu]
> > Sent: Thursday, March 21, 2002 11:00 AM
> > To: jimi adams
> > Cc: r-help at stat.math.ethz.ch
> > Subject: Re: [R] how does while work
> > 
> > 
> > On Wed, 20 Mar 2002, jimi adams wrote:
> > 
> > > i am having some problems with a program that i am writing 
> > and i think that
> > > knowing how the while command works will help me to figure 
> > out where i am
> > > going wrong
> > > *when do you get kicked out of a while loop?*
> > > (i.e., in the following example  what would the final value 
> > of 'a' be?) i
> > > thought it would be 99 but running it in R i get 101 (and 
> > 101 for x too!)
> > > 
> > > while (x <100) {
> > >   for (i in 1:101) {
> > >     i -> x
> > >     x -> a
> > >   }
> > > *here*  
> > > }
> > 
> > Essentially the while condition doesn't get checked until 
> > just before the
> > last curly brace (where I inserted *here* above), so the for 
> > loop gets to
> > do it's thing until i (and x and a) reach 101 and only then 
> > is the while
> > condition allowed to drop you out of the loop.
> > 
> > > while this is a crude example, it is the basic form of what 
> > i am trying to
> > > do, and i am guessing that while is not what i am looking for...
> > 
> > what exactly are you trying to do?
> > 
> > daver
> > 
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-- 

 __________________________________________________
[                                                  ]
[ Giovanni Petris                 GPetris at uark.edu ]
[ Department of Mathematical Sciences              ]
[ University of Arkansas - Fayetteville, AR 72701  ]
[ Ph: (479) 575-6324, 575-8630 (fax)               ]
[ http://definetti.uark.edu/~gpetris/              ]
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