I am trying to run the following code:
$lines = "Enjoyable )) DAY";
$lines =~ lc $lines;
print $lines;
It fails on the second line where I get the error mentioned in the title. I understand the brackets are causing the trouble. I think I could use "quotemeta", but the thing is that my string contains info that I go on to process later, so I would like to keep the string intact as far as possible and not tamper with it too much.
You have two problems here.
1. =~ is used to execute a specific set of operations
The =~ operator is used to either match with //, m//, qr// or a string; or to substitute with s/// or tr///.
If all you want to do is lowercase the contents of $lines then you should use = not =~.
$lines = "Enjoyable )) DAY";
$lines = lc $lines;
print $lines;
2. Regular expressions have special characters which must be escaped
If you want to match $lines against a lower case version of $Lines, which should return true if $lines was already entirely lower case and false otherwise, then you need to escape the ")" characters.
#!/usr/bin/env perl
use strict;
use warnings;
my $lines = "enjoyable )) day";
if ($lines =~ lc quotemeta $lines) {
print "lines is lower case\n";
}
print $lines;
Note this is a toy example trying to find a reason for doing $lines =~ lc $lines - It would be much better (faster, safer) to solve this with eq as in $lines eq lc $lines.
See perldoc -f quotemeta or http://perldoc.perl.org/functions/quotemeta.html for more details on quotemeta.