That isn't right. It isn't that $file =~ $string is always true, it is that in for ( ... ), you never get to the inner guts of the for() if there is nothing in @strings. It is also true that  ... =~ // is also true. Maybe you had a blank line in your input.

I've included a slightly different and to my mind nicer version of your code. You may find it helpful.

my $pattern_file = <STDIN>;
chomp $pattern_file;

open my $patterns, "<", $pattern_file or die "Can't open '$pattern_fil
+e' for reading: $!";
my @patterns = <$patterns>;
chomp @patterns;
@patterns = grep length(), @patterns;
@patterns = map qr/$_/, @patterns;

...

foreach my $file ( ... )
{
    # All patterns must match
    foreach my $pattern ( @patterns )
    {
        next if $file =~ $pattern;

        print OUT "'$file' !~ /$pattern/\n";
        last;
    }
}

[download]

In reply to Re: Help with null string behavior in regex? by diotalevi
in thread Help with null string behavior in regex? by McMahon

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