Hello dirtdog,

First, you have the logic back-to-front; you want:

next if !$ex_date;
next if !defined($ex_date);

[download]

or

next unless ex_date;
next unless defined($ex_date);

[download]

Second, the two statements are not equivalent. The first will skip to the next record if $ex_date has the value of 0 (zero), "" (the null string), or undef. See perlsyn#Truth-and-Falsehood. The second statement will skip only if $ex_date is undef.

Which form to use depends on how you define “null.” If by null you mean false, then use the first form; but if you mean undefined, then the second form is the one you want. Without more information, it’s difficult to guess which meaning of “null” best suits your needs; but the second interpretation (null means undef) is usually the safer option.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re: Checking Variable for Not Null by Athanasius
in thread Checking Variable for Not Null by dirtdog

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