Re... quick question about parentheses and regular expressions


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Re... quick question about parentheses and regular expressions

by Roy Johnson (Monsignor)

on Nov 04, 2003 at 18:08 UTC ( [id://304494]=note: print w/replies, xml )

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in reply to Re: Re: Re: quick question about parenthesis and regular expressions
in thread quick question about parenthesis and regular expressions

You're right: the \bs in the pattern do seem to sabotage $1. In particular, any char in front of the () group kills the $1, if the g and i switches are both set.

my $line = 'She was very absorbed in her homework.';
my $word = 'absorb';

$_=$line;
s/ ($word)//g;
print "\$1 is $1\n";
$_=$line;
s/ ($word)//i;
print "\$1 is $1\n";
$_=$line;
s/ ($word)//ig;
print "\$1 is $1\n";
[download]

One other note:

#This also fails
s/(\b$word)//ig;
#Although this is ok
s/( $word)//ig;
#And this is fine, too!
my $pat = qr/\b($word)/;
s/$pat//gi;
#or even
my $pat = qr/($word)/;
s/\b$pat//gi;
#or EVEN THIS!
my $pat = qr/$word/;
s/\b($word)//gi;
[download]

I think we have a perlbug. Frenzy of updates completed. Really.