foreach loop bug

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

Hi,

The following loop crashes when @allc has records in the form of abc2000@***** (with asterix).

foreach $i (@allc) {
  chomp($i);
  if($i eq "aa\@xx.com") { next; }
  else {
    if($who =~ $i) { print qq(one $i); }
    else { print qq($i); }
  }
}
[download]

Why is this crashing??? Something seems to be very buggy here.

- Ralph.

2003-06-10 edit ybiC: <code> and <tt> tags

Comment on foreach loop bug Download Code

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Re: foreach loop bug by davorg (Chancellor) on Jun 10, 2003 at 10:29 UTC
Because Perl is seeing the '' as regex quantifiers. Use `\Q` to prevent that. `if($who =~ /\Q$i/) { print qq(one $i); } else { print qq($i); }` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club."* -- Chip Salzenberg	[reply] [d/l]
Re: foreach loop bug by diotalevi (Canon) on Jun 10, 2003 at 10:25 UTC
There is no particular reason that should "crash". What you are likely running into is that you haven't properly escaped the regex-special sequences and characters like asterisks. Try making the simple change of instead of `$who =~ $i` write `$who =~ /\Q$i/` which will escape the asterisks from 'abc2000@****' to 'abc2000\@\\\\\' automatically. See also "quotemeta" in perlop.	[reply] [d/l] [select]
Re: foreach loop bug by adrianh (Chancellor) on Jun 10, 2003 at 10:29 UTC
It's crashing because the asterix characacters are being interpreted as regular expression characters (when you do `$who =~ $i`). With the code you've given it's hard to see what you're trying to do here - so I'm not sure what the correct fix would be.	[reply] [d/l]
Re: foreach loop bug by Anonymous Monk on Jun 10, 2003 at 10:50 UTC
Thanks for waking me up :-p Just fixed it. I guess I didn't see that error since I was feeding a variable instead of trying to do $who =~ '**'. So the error wasn't so visible. Thanks, Ralph	[reply]