A scalar isn’t the only kind of return value a subroutine may have. If you call your subroutine in a list context,[112] it can return a list of values.
Suppose you wanted to get a range of numbers (as from the range operator, ..
) except that you want to be able to count down as well as up. The range operator only counts upward, but that’s easily fixed:
sub list_from_fred_to_barney { if ($fred < $barney) { # Count upwards from $fred to $barney $fred..$barney; } else { # Count downwards from $fred to $barney reverse $barney..$fred; } } $fred = 11; $barney = 6; @c = &list_from_fred_to_barney; # @c gets (11, 10, 9, 8, 7, 6)
In this case, the range operator gives us the list from 6
to 11
, and reverse
reverses the list, so it goes from $fred
(11
) to $barney
(6
) just as we wanted.
The least you can return is nothing at all. A return
with no arguments will return undef
in a scalar context or an empty list in a list context. This can be useful for an error return from a subroutine, signalling to the caller that a more meaningful return value is unavailable.
[112] You can detect if a subroutine is being evaluated in a scalar or list context using the wantarray
function, which lets you easily write subroutines with specific list or scalar context values.
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