The difference between undef and an empty string is exactly the same as the difference between (SQL) NULL and an empty string:

undef means "I don't know what the value is or even if there is a value".

empty string means "I know what the value is, and it is nothing".

In reply to Re: difference b/w undef and empty string by dsheroh
in thread difference b/w undef and empty string by saranperl

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