ahh great, you all cleared it up perfectly for me, thank you. that perlfaq
section was great also.
Philipp Traeder wrote:
> On Friday 09 July 2004 19:25, Gunnar Hjalmarsson wrote:
>> Philipp Traeder wrote:
>> > I don't know what an expert would say,
>>
>> Neither do I. :)
>
> I think this is a good base for talking about hashes. ;-)
>
>> > but for testing if a hash contains an element, I normally use
>> > "exists":
>>
>> Your wording "if a hash contains an element" is ambigous IMO. A hash
>> or associative array consists of key/value pairs, where the keys are
>> indexes and the values are considered to be the elements (I think).
>
> Ok - that's a possible terminology, and yes, I wasn't completely precise
> ;-)
>
>>
>> > if (exists ($hash{'mykey'})) {
>> > print 'mykey exists.';
>> > }
>>
>> That's fine, as long as you are aware that $hash{mykey} may well be
>> undefined even if it "exists".
>
> I think *this* is the interesting point here - it's quite possible that a
> certain key exists in a hash, but has an undefined value:
>
> my %hash = (42 => undef);
>
> print "42 exists\n" if (exists $hash{42});
> print "42 is defined\n" if (defined $hash{42});
>
> If you ask me, you can't put up a general rule about using "exists" or
> "defined" - it's a questions of how/on which conditions the hash has been
> filled...
>
> Just my 5 cent,
>
> Philipp
>
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