Optimisation

[Chris Jack]

> On Mon, Mar 2, 2009 at 9:01 PM, Nigel Peck <nigel.peck at miswebdesign.com> wrote:
> >
> > When the list could be empty, which is faster?
> >
> > if ( @list ) { foreach ( @list ) { } }
> >
> > - or just -
> >
> > foreach ( @list ) { }
> >
> > Or is it a pointless question?

 

 

The chances that the formatting up in the following stuffs up from hotmail's html being converted to text are high. If I run the following:

 

 

my @list;


my $k;


my $i = 0;


while ($i < 10000000) {


  if (@list) {


    for $k (@list) {


      print $k;


    }


  }


  $i++;


}

 

 

it takes 8.315 seconds. If I remove the "if (@list)" and rerun it, it takes 11.781 seconds. If I rerun the same two tests but with one element in the list the timings go to 25.337 seconds and 21.704 seconds respectively - so you would only expect an improvement if over 50% of your cases had an empty list.

 

 

But I agree with most of the other comments. I had to put the loop up to 10 million to get meaningful timings and life is to short to save 3 seconds on 10 million interations - and it's much clearer and readable without the "if".

 

 

Chris


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