Re: Adding Unique Elements to Array

Does the order of the elements matter? If not, you could use hash keys instead.

my %h;
for(qw/foo bar baz quux foo narf bar poit/) {
    $h{$_} = 1;
}
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If the order matters, you could keep a separate hash that has all of the items in it as keys.

my (%h, @a);
for(qw/foo bar baz quux foo narf bar poit/) {
    push @a, $_ unless exists $h{$_};
    $h{$_} = 1;
}
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Comment on Re: Adding Unique Elements to Array Select or Download Code

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Re^2: Adding Unique Elements to Array by ww (Archbishop) on Feb 28, 2005 at 19:57 UTC
Recall, however, that "last in wins" when populating a hash. OP appears to want not only to assure uniqueness (without testing) but also "only allow the value onto the array if it is not already included." (emphasis mine)	[reply]
Re^3: Adding Unique Elements to Array by friedo (Prior) on Feb 28, 2005 at 20:06 UTC
But neither of the above solutions puts the elements in hash values. Either we're using the keys as an unsorted array directly, or using the keys as a separate boolean record of what's already in there.	[reply]
Re^2: Adding Unique Elements to Array by thekestrel (Friar) on Feb 28, 2005 at 18:46 UTC
Thanks Friedo, The order does not matter actually, and as I was posting I was thinking about the use of a hash, just populating it with dummy data for key manipulation bothered me for some reason. Now that I think about it though that might be the best way to do it. Thanks =) Regards Paul	[reply]
Re^3: Adding Unique Elements to Array by melora (Scribe) on Feb 28, 2005 at 18:58 UTC
That's the way I do it. It avoids having to test for duplicates (in my code, anyway). Also, if I need 'em in order I can use sort keys.. I'm relieved to see that mentioned here. I was afraid I was the only one doing it, and that there was a far better way.	[reply]