Perl regex: combining ^ with \Q \E

Asked Jun 27 '18 at 12:37

Active Jun 27 '18 at 12:52

Viewed 28 times

I'm finding that when I combine ^ with \Q \E in Perl regex, I no longer get matches that I should be getting:

$names = "20170101--NAME1-NAME2";
@list = ( '20170101--NAME1-NAME2-bt123456789.xml', 
          '20170101--NAME1-NAME2-bt234567890.xml');
@numbers = ( '123456789', '234567890' );

for my $filename (@list) {
    if ($filename =~ /\Q$names\E-bt[^\Q$numbers[0]\E]\.xml/) {
        print "$filename\n";
    }
}

This gives 0 matches, but should match '20170101--NAME1-NAME2-bt234567890.xml'. If I change the regex in the if statement to:

/\Q$names\E-bt(\Q$numbers[0]\E)\.xml/

This returns:

'20170101--NAME1-NAME2-bt123456789.xml'

I know it's not matching the same thing as my original regex, just proving that the regex works without the ^. I also tried the following just in case:

^[\Q$numbers[0]\E] # 0 matches
(^\Q$numbers[0]\E) # 0 matches

edited Jun 27 '18 at 12:52

asked Jun 27 '18 at 12:37

jen

1

`^` matches the start of the string. – Wiktor Stribiżew Jun 27 '18 at 12:39
That's true, but inside brackets e.g. [^abc] should match any string not containing abc. I'm finding that this doesn't work if \Q \E is introduced. – jen Jun 27 '18 at 12:43
1

`[^abc]` matches any *char* not equal to `a`, `b`and `c`. `^` is not inside `[...]` in your pattern, it is a start of string anchor. – Wiktor Stribiżew Jun 27 '18 at 12:44
Yes, but I also stated that I tried it inside the brackets, and it still returned 0 matches. I'll edit my question to make it clearer. – jen Jun 27 '18 at 12:46
Ok, your input string contains no `^` chars. – Wiktor Stribiżew Jun 27 '18 at 12:46

Perl regex: combining ^ with \Q \E

0 Answers0