Without changing the original,how do we perform a replacement on a string using perl regex?

Method1:

 

(my $newstring = $oldstring) =~ s/foo/bar/g;

Method2:

 

my $newstring = $oldstring =~ s/foo/bar/gr;   

Method3:

 

if it is an arrays:

my @a = ('appl', 'appl bal', 'fruit?');

my @b = map { s/appl/apple/; $_ } map { $_ } @a;

 

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