regex to substitute 3 stars at beginnning of string with none?

princepawn has asked for the wisdom of the Perl Monks concerning the following question:

For some reason, printing out $1 only prints 1 star when the regex $HAIR is clearly matching 3 stars

For some reason, my attempt to replace 3 stars at the start of a string with the empty string is clearning the whole string.

Could someone please help me with this? Thanks!

my @question;

sub make_question {
  my ($question,@answer) = @_;
  [ $question, \@answer ];
}

push @question, make_question
'What is an example of autovivification in Perl?',
  '***my %x; $x{y}->[2]->{jum} ;',
  'sub y { my ($self,$x) = @_ }',
  'my $end = ($end > rand) ? $end : rand;';
  ;
  
for (@question) {
  printf "Question %d: %s\n", ++$count, shift @$_;
  my $HAIR = '^([*]){3}';
  my $count;
  for my $answer (@{$_->[0]}) {
    if ($mode eq 'key') {
      if ($answer =~ /$HAIR/) {
         $answer = $1;
      } else {
         $answer = '';
      }
    } else {
      $answer = s/$HAIR//;
   }
    printf "\t%d. %s\n", ++$count, $answer;
  }

  print "\n";
}
[download]

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Re: regex to substitute 3 stars at beginnning of string with none? by Sprad (Hermit) on Apr 23, 2001 at 21:40 UTC
Ready to kick yourself? Change `$answer = s/$HAIR//;` to `$answer =~ s/$HAIR//;` --- I'm too sexy for my .sig.	[reply] [d/l] [select]
Re: Re: regex to substitute 3 stars at beginnning of string with none? by suaveant (Parson) on Apr 23, 2001 at 21:44 UTC
Heehee, I missed that one... very important distinction :) - Ant	[reply]
Re: Re: regex to substitute 3 stars at beginnning of string with none? by princepawn (Parson) on Apr 23, 2001 at 21:42 UTC
Thanks. That works perfectly. -- That light at the end of the tunnel is the headlights of an approaching train.	[reply]
Re: regex to substitute 3 stars at beginnning of string with none? by suaveant (Parson) on Apr 23, 2001 at 21:32 UTC
`'^([]){3}'` has the {3} on the outside of the (), so it is match `([]}` many times, each time saving a single ... you need to move them inside `'^([]{3})'` then you will be happier. - Ant	[reply] [d/l] [select]
Re: Re: regex to substitute 3 stars at beginnning of string with none? by buckaduck (Chaplain) on Apr 24, 2001 at 00:55 UTC
Update: A quick test confirms what merlyn says below. I have to admit that the correct behavior surprised me, but sounds sensible in retrospect. Here's my original post, anyway: To clarify: `([]){3}` is like `([])([])([])` That means that $1, $2, $3 each contain one of the asterisk characters. The suggested solution `([*]{3})` has all three characters inside the same set of parentheses, and therefore saves them all into $1. buckaduck	[reply] [d/l] [select]
Re: Re: Re: regex to substitute 3 stars at beginnning of string with none? by merlyn (Sage) on Apr 24, 2001 at 00:58 UTC
No, `([]){3}` is like `(?:\)(?:\)(\)`. You'll have only $1, and it's the result of the final inner match. -- Randal L. Schwartz, Perl hacker	[reply] [d/l] [select]
Re: regex to substitute 3 stars at beginnning of string with none? by Corion (Patriarch) on Apr 23, 2001 at 21:36 UTC
`$1` really matches only one star. If you want to capture all three stars in $1, you must use `^([*]{3})` (note that the `{}` quantifier has moved into the capturing parentheses).	[reply]
Re: regex to substitute 3 stars at beginnning of string with none? by princepawn (Parson) on Apr 23, 2001 at 21:38 UTC
'^(){3}' has the {3} on the outside of the (), so it is match (} many times, each time saving a single ... you need to move them inside '^({3})' then you will be happier. For key mode, your answer is correct and I am indeed happier. However, for test mode (when the substitution is run on `$HAIR`, the whole string is still wiped out!	[reply] [d/l]