($sEnd) = map {s/hello/goodbye/g; $_;} map {$_} ($sBegin);

##</code><code>##

($sEnd) = map {s/hello/goodbye/g; $_;} @{[$sBegin]};

##</code><code>##

$sEnd = do {local $_ = $sBegin; s/hello/goodbye/g; $_;};

##</code><code>##

(my $sEnd = $sBegin) =~ s/hello/goodbye/g;