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Re: use of array_key_exists() to prevent duplicates? [message #173039 is a reply to message #173038]

Fri, 18 March 2011 16:15

Captain Paralytic
Messages: 204
Registered: September 2010

Karma:

Senior Member

On Mar 18, 3:06 pm, William Gill <nos...@domain.invalid> wrote:
> On 3/18/2011 6:05 AM, Captain Paralytic wrote:
>
>
>
>
>
>
>
>> On Mar 17, 5:09 pm, William Gill<nos...@domain.invalid> wrote:
>>> On 3/17/2011 11:58 AM, Captain Paralytic wrote:
>
>>>> Alternative 1) Just assign the values to an associative array with the
>>>> serial number as the key. At the end a foreach will produce a list of
>>>> unique values. No need for array_key_exists() at all.
>
>>> Is this any more efficient than if (array_key_exists()) ?
>>> On the minus side, if I edit or modify the memo, it will be overwritten
>>> using this alternative. I could avoid this, but it seems unnecessarily
>>> complicated.
>> Not complicated at all. My original suggestion keeps the last copy. If
>> they are "duplicates" then they will all be the same. If instead you
>> want the first copy you just add an if test as in
>> if(!isset($myarray[$mykey]))
>> $myarray[$mykey] = $myvalue;
>
> Yes, after I spoke I realized that it didn't have to be too complicated,
> but I still have to ask: is there any advantage to testing for isset()
> as opposed to testing for array_key_exists() (besides the treatment of
> NULL values), or are you just posing an equally viable alternative?

Well actually I'm not clear from your OP what you really need. If the
source program produces duplicates of old records as well as new ones,
then provided that the new records come after the old ones, I would
assume that the one you wanted to end up with was the latest one and
so you would not want to use either array_key_exists() or isset().

If you want the first occurrence then all the benchmark tests show
isset() being much more efficient than array_key_exists().

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[Message index]

		use of array_key_exists() to prevent duplicates? By: William Gill on Thu, 17 March 2011 15:35
		Re: use of array_key_exists() to prevent duplicates? By: Captain Paralytic on Thu, 17 March 2011 15:58
		Re: use of array_key_exists() to prevent duplicates? By: William Gill on Thu, 17 March 2011 17:09
		Re: use of array_key_exists() to prevent duplicates? By: Captain Paralytic on Fri, 18 March 2011 10:05
		Re: use of array_key_exists() to prevent duplicates? By: William Gill on Fri, 18 March 2011 15:06
		Re: use of array_key_exists() to prevent duplicates? By: Captain Paralytic on Fri, 18 March 2011 16:15
		Re: use of array_key_exists() to prevent duplicates? By: William Gill on Fri, 18 March 2011 16:34
		Re: use of array_key_exists() to prevent duplicates? By: Captain Paralytic on Fri, 18 March 2011 16:46
		Re: use of array_key_exists() to prevent duplicates? By: William Gill on Fri, 18 March 2011 17:17

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