An idea for you:
use strict; use warnings; my $foo ="some hello message"; my ($hello) = $foo =~ /(hello)/; $hello //= ''; # null string if "hello" was not found __END__ $hello will be either "hello" or a null string. Better than an undef value. Amongst other things, this maintains a "printable value" for $hello. use $hello in a Boolean context. $foo is a string. Do not reuse that string variable name to mean something different. Create new Boolean variable.