Question

I have a string, say: “5 3*3 4*1 6*3 14*4 3*2 2*3 4”

I want this string to become an array with elements:

@array = ( “5”, “3” x 3, “1” x 4, “3” x 6, “4” x 14, “2” x 3, “3” x 2, “4” );

I’m guessing there’s a better (shorter) way than this:

$string = "5 3*3 4*1 6*3 14*4 3*2 2*3 4";
@array = split (/\s+/,$string);
foreach(@array) {
   if ( /\*/ ) {
      s/^(\d+)\*(\d+)/"$2" x $1/g;
   } else {
      print "$_\n";
      $_ = '"'. $_ .'"';
   }
}

EDIT: This code actually does what I say it should do above in the original question. But it’s not actually what I want. I want the final array to look like:

@array = (5, 3, 3, 3, …)

Answer 1

Algorithm:

1. Take the string and split it at spaces
2. If the /(\d+)*(\d+)/ regex matches an element, we do the list element repetition. Else, we pass the element through unchanged.

Implementation (oneliner)

perl -MData::Dumper -E'$string = "5 3*3 4*1 6*3 14*4 3*2 2*3 4"; @array = map{/(\d+)\*(\d+)/ ? ($2)x$1 : $_} split /\s+/, $string; say Dumper \@array'

Implementation (normal)

my $string = "5 3*3 4*1 6*3 14*4 3*2 2*3 4";
my @array = map {/(\d+)\*(\d+)/ ? ($2)x$1 : $_} split /\s+/, $string;
# do something with @array:
say "@array";

Do note that the repetition operator used on strings repeats and concatenates the strings:

"a"x3 ~~ "aaa"

But used on a list, it returns a list with repeated elements:

[(1)x3] ~~ [1,1,1]
[(1,2)x2] ~~ [1,2,1,2]