Question

Let’s say I have string ‘The quick brown fox jumps over the lazy dog’ can I change this to ‘The slow brown fox jumps over the energetic dog’ with one regular expression? Currently, I use two sets of regular expressions for this situation. (In this case, I use s/quick/slow/ followed by s/lazy/energetic/.)

Answer 1

The second part of a substitution is a double quoted string, so any normal interpolation can occur. This means you can use the value of the capture to index into a hash:

#!/usr/bin/perl  use strict; use warnings;   my %replace = (     quick => 'slow',     lazy  => 'energetic', );  my $regex = join '|', keys %replace; $regex = qr/$regex/;  my $s = 'The quick brown fox jumps over the lazy dog';  $s =~ s/($regex)/$replace{$1}/g;  print '$s\n';