I am now able to exclude and reform $B, but I can't do it the other way (include only "def"). Isn't "while" suppose to be the opposite of "until"?

#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;

my $B = "";
my $A = "abc
def
ghi
";

while ( $A =~ m{(.+)}g ) {
   $B .= "$1\n" unless $1 =~ /def/;
}
print "\$B = \n$B\n";


$B = "";
while ( $A =~ m{(.+)}g ) {
   $B .= "$1\n" while $1 =~ /def/;
}
print "\$B = \n$B\n";

[download]

$B =

abc

ghi

Use of uninitialized value $_ in pattern match (m//) at ./ExtractTest.pl line 21 (#1)

Now what am I doing wrong?

In reply to Re^4: Regex match on implicit default variable ($_) in a script, not a one liner by Todd Chester
in thread Regex match on implicit default variable ($_) in a script, not a one liner by Todd Chester

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