#!/usr/bin/perl

my $s0 = "red apple";
my $s1 = $s0;

print "s0 = $s0\n";

my $k = 0;
my $pattern = qr/(.)ed/;

$s0 =~ s/$pattern/++$k && "$1osy"/ge;

print "$k change(s)\n";
print "s0 = $s0\n";

$k = 0;

$pattern = qr/r(.)(.)/;
my $replace = '$2ead';

$s1 =~ s/$pattern/++$k && $replace/ge;

print "$k change(s)\n";
print "s1 = $s1\n";