Posted by Jerry Stuckle on 05/20/07 14:23

Jon Slaughter wrote:
> "Jerry Stuckle" <jstucklex@attglobal.net> wrote in message
> news:lcWdnQnjjd1qKdLbnZ2dnUVZ_oLinZ2d@comcast.com...
>> Schraalhans Keukenmeester wrote:
>>> At Fri, 18 May 2007 21:05:36 -0400, Jerry Stuckle let his monkeys type:
>>>
>>>> ZeldorBlat wrote:
>>>>> On May 18, 11:40 am, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com>
>>>>> wrote:
>>>>>> "ZeldorBlat" <zeldorb...@gmail.com> wrote in message
>>>>>>
>>>>>> news:1179501018.125313.63600@p77g2000hsh.googlegroups.com...
>>>>>>
>>>>>>> On May 18, 11:05 am, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com>
>>>>>>> wrote:
>>>>>>>> Is it safe to remove elements from an array that foreach is working
>>>>>>>> on?
>>>>>>>> (normally this is not the case but not sure in php) If so is there
>>>>>>>> an
>>>>>>>> efficient way to handle it? (I could add the indexes to a temp array
>>>>>>>> and
>>>>>>>> delete afterwards if necessary but since I'm actually working in a
>>>>>>>> nested
>>>>>>>> situation this could get a little messy. I guess I could set there
>>>>>>>> values
>>>>>>>> to
>>>>>>>> null and remove them afterwards?
>>>>>>>> Thanks,
>>>>>>>> Jon
>>>>>>> Why don't you try it and see what happens?
>>>>>> Um... cause I did... but that doesn't mean much. Just cause someone
>>>>>> tries
>>>>>> something doesn't prove that it will always work like that...
>>>>>>
>>>>>> got any more bright ideas?
>>>>>>
>>>>>> Or is the question to hard for you?
>>>>> No, the question is not to (sic) hard for me. But, as you've already
>>>>> discovered, it isn't that difficult to test, either.
>>>>>
>>>> Sorry, I agree with Jon on this one.
>>>>
>>>> I make it a habit not to delete entries in a foreach() loop. Rather, I
>>>> build an array of keys I want to delete, and after the loop ends, delete
>>>> the entries from my delete array.
>>>>
>>>> I don't know whether an operation like this is guaranteed to work in
>>>> PHP - I've never seen it documented, so I suspect not. And just because
>>>> it works in one release under a certain set of conditions is not a
>>>> guarantee it will work on another release or under different conditions.
>>> I agree 100% with you not to rely on undocumented 'features'.
>>> Just out of curiosity I took this one step further and discovered the
>>> following (again, can't rely on this to hold true unless it's documented
>>> somewhere, well hidden):
>>>
>>> <?PHP
>>> $array=array('john','james','delilah','mary');
>>> foreach ($array as $key=>$value) {
>>> echo "$key => $value".NEWLINE;
>>> if ($value == 'delilah') {
>>> $array[$key]='samson';
>>> } elseif ($value=='james') {
>>> unset($array[$key]);
>>> }
>>> }
>>> echo NEWLINE;
>>> foreach ($array as $key=>$value) {
>>> echo "$key => $value".NEWLINE;
>>> }
>>> ?>
>>> 0 => john
>>> 1 => james
>>> 2 => delilah
>>> 3 => mary
>>>
>>> 0 => john
>>> 2 => samson
>>> 3 => mary
>>>
>>> The foreach loop operates on a copy of the array
>>> The original array remains in scope
>>> Current($array) points to the first element throughout the loop
>>>
>>> I'd think setting elements to NULL directly in the array isn't any
>>> better,
>>> you're still relying on the same 'feature'.
>>>
>>> Sh
>> Yes, foreach() works on a copy. But while the manual indicates changes to
>> the copy don't affect the original - they say nothing about when changes
>> to the original will affect the copy.
>>
>
> since its a copy the original should effect in any way the copy?
>
> I could only see this if the copy is not a deep copy.... but in php all
> copies are deep?
>
>

There is nothing indicating when the copy is updated from the original.
It might be only at the beginning, everything through the loop or
anything else.

It's not documented - so you can't depend on the operation.

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

[Back to original message]