qr operator - create a regular expression reference - Perl ABC - Perl Installation, Perl Tutorial, Many Examples

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qr operator - create a regular expression reference

You can create regular expression reference with the qr operator . You can use the qr operator to save a regular expression as a reference in a variable. You can also save regular expression options. Regular expressions are compiled, so they work faster when doing repeated pattern matching.

# Regular expression reference
my $regex = qr/\d+/sm;

When performing pattern matching, you can put it in // or use it as it is. I think it's a little easier to see if you put it in //.

# Used in //
if ($str =~ /$regex/) {
  ...
}

# Use as it is
if ($str =~ $regex) {
  ...
}

What is a reference?

The reference is explained in detail in the following article.

Let's master how to use reference

Example

This is an example using a regular expression reference.

use strict;
use warnings;

# You can use qr // to save the options as well.
# (The g option cannot be specified.)
my $word = "ababab";
my $regex = qr/A/i;
                    
my $replace = 'c';

$word =~ s/$regex/$replace/g;
print "\$word = $word\n";

Output.

$word = cbcbcb

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