Re: Inserting into an array while stepping through it

Maybe a good use for the function map. Layman's terms: It applies a sub to each item of a list, and it returns a list of all the sub results. Okay, a better example: You have a list with numbers, you want a list of each number, times 3.

my @list = ( 5, 11, 7);
my @timesthree = map { $_ *= 3 } (@list);
[download]

or if you only want to operate on multiples of five:

my @timesthree_onlyfives = map { $_ *= 3 if ($_ % 5 == 0) } (@list);
[download]

BUT, you will get a list of one item! so you want:

my @all_timesthree_onlyfives = 
   map { 
      if ($_ % 5 ==0) {
         $_ *= 5;
      } else {
         return $_;
      }
   } (@list);
[download]

But that could be done better.

Hope I've described it well, and HTH!

mhoward - at - hattmoward.org

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Re: Re: Inserting into an array while stepping through it by sauoq (Abbot) on Jun 13, 2003 at 02:43 UTC
Well, `map()` is a good alternate solution (though it wouldn't be doing the modification in place exactly.) But, you didn't show how to use it in the way he wants to... `@list = map { $_ eq 'condition' ? my_sub( $_ ) : $_ } @list;` [download] and yes, that'll work when `my_sub()` returns a list too. -sauoq "My two cents aren't worth a dime.";	[reply] [d/l]
Re: Re: Re: Inserting into an array while stepping through it by meredith (Friar) on Jun 13, 2003 at 02:52 UTC
Thanks for the code -- I just wanted to include an explanation for the code I posted, instead of a one-liner and some code. Anonymous Monk sure posts a lot of questions, and I want to help him learn. ;) Besides, everyone knows that using map scores you extra Perl Points(tm)!! `mhoward - at - hattmoward.org`	[reply]