comment on

While the case of '--' and ';' seems to be a matter of debate and jocose comment, you might like to know that you can switch case sensitivity on and off in different parts of a regular expression. You would use constructs like (?i), (?-i), (?i:text) and (?-i:text). The first two switch case insensitivity on and off respectively. The second two just apply their effect, insensitive or sensitive respectively, to the text inside the parentheses. Here is a contrived example that uses a precompiled (qr{ ...}) regular expression that also uses extended syntax, the x, to allow comments and white space inside the expression.

use strict;
use warnings;

my @strings = (
   q{catFiSHcake},
   q{DogFISHcAkE},
   q{cATfishCake},
   q{caTFISHcaKE});

my $rxMixed = qr
   {(?xi)           # use extended syntax and
                    #   make case insensitive
       (?:cat|dog)  # non-capture alternation
                    #   of cat or dog
       (?-i:FISH)   # FISH, case sensitive
                    #   inside parentheses
       cake         # cake, case insensitive
                    #   again
   };

foreach my $string ( @strings )
{
    print
       qq{$string: },
       $string =~ $rxMixed
       ? qq{Match\n}
       : qq{No match\n};
}
[download]

Here's the output.

catFiSHcake: No match
DogFISHcAkE: Match
cATfishCake: No match
caTFISHcaKE: Match
[download]

I hope this is of interest.

Cheers,

JohnGG

In reply to Re^3: Making a regex case insensitive by johngg
in thread Making a regex case insensitive by Win

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