two hash tables, keys comparision?

let's say I have two hash tables: new, old

How to find out the keys in new, but not in old?
How to find out the keys in old, but not in new?

tell me the quickest way.

Thanks.

Re: two hash tables, keys comparision?

"robertchen117@gmail.com" writes:

> How to find out the keys in new, but not in old?
> How to find out the keys in old, but not in new?
>
> tell me the quickest way.

What have you tried?

Re: two hash tables, keys comparision?

"robertchen117@gmail.com" wrote:
>
> let's say I have two hash tables: new, old
>
> How to find out the keys in new, but not in old?

my @keys_in_new_not_old = grep !exists $old{$_}, keys %new;


> How to find out the keys in old, but not in new?

my @keys_in_old_not_new = grep !exists $new{$_}, keys %old;




John
--
use Perl;
program
fulfillment

Re: two hash tables, keys comparision?

robertchen117@gmail.com wrote:
> let's say I have two hash tables: new, old
>
> How to find out the keys in new, but not in old?
> How to find out the keys in old, but not in new?
>
> tell me the quickest way.

Such a politely phrased request...

BugBear

Re: two hash tables, keys comparision?

On Nov 28, 10:04 am, bugbear
wrote:
> robertchen...@gmail.com wrote:
> > let's say I have two hash tables: new, old
>
> > How to find out the keys in new, but not in old?
> > How to find out the keys in old, but not in new?
>
> > tell me the quickest way.
>
> Such a politely phrased request...
>
> BugBear

He did say "Thanks"

Re: two hash tables, keys comparision?

smallpond wrote:
> On Nov 28, 10:04 am, bugbear
> wrote:
>> robertchen...@gmail.com wrote:
>>> let's say I have two hash tables: new, old
>>> How to find out the keys in new, but not in old?
>>> How to find out the keys in old, but not in new?
>>> tell me the quickest way.
>> Such a politely phrased request...
>>
>> BugBear
>
> He did say "Thanks"

A little backwards, but I take your point.

BugBear

Re: two hash tables, keys comparision?

smallpond wrote in news:85356d58-b29b-45cc-871c-
c3327efbe1db@i12g2000prf.googlegroups.com:

> On Nov 28, 10:04 am, bugbear
> wrote:
>> robertchen...@gmail.com wrote:
>> > let's say I have two hash tables: new, old
>>
>> > How to find out the keys in new, but not in old?
>> > How to find out the keys in old, but not in new?
>>
>> > tell me the quickest way.
>>
>> Such a politely phrased request...
>>
>> BugBear
>
> He did say "Thanks"

where he should have said *please*.

Sinan

--
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