in reply to Re: difference b/w undef and empty string
in thread difference b/w undef and empty string

That may be true in a scalar context, but a point about list context:
In a list context: undef means I know that there is something that is supposed to be here and I don't know what it is (undef IS a value!), '' or "" means null (empty)string which is also a value, meaning "empty".
So in list or array context, undef means there is a value, but it is unknown.
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