2008/11/20 Stut <stuttle@xxxxxxxxx>:
> On 20 Nov 2008, at 06:55, Yashesh Bhatia wrote:
>>
>> I wanted to use in_array to verify the results of a form submission
>> for a checkbox and found an interesting
>> behaviour.
>>
>> $ php -v
>> PHP 5.2.5 (cli) (built: Jan 12 2008 14:54:37)
>> $
>>
>> $ cat in_array2.php
>> <?php
>> $node_review_types = array(
>> 'page' => 'page',
>> 'story' => 'story',
>> 'nodereview' => 'abc',
>> );
>>
>> if (in_array('page', $node_review_types)) {
>> print "page found in node_review_types\n";
>> }
>> if (in_array('nodereview', $node_review_types)) {
>> print "nodereview found in node_review_types\n";
>> }
>>
>> ?>
>> $ php in_array2.php
>> page found in node_review_types
>> $
>>
>> This works fine. but if i change the value of the key 'nodereview' to
>> 0 it breaks down.
>>
>> $ diff in_array2.php in_array3.php
>> 6c6
>> < 'nodereview' => 'abc',
>> ---
>>>
>>> 'nodereview' => 0,
>>
>> $
>>
>> $ php in_array3.php
>> page found in node_review_types
>> nodereview found in node_review_types
>> $
>>
>> Any reason why in_array is returning TRUE when one has a 0 value on the
>> array ?
>
> That's weird, 5.2.6 does the same thing. There's actually a comment about
> this on the in_array manual page from james dot ellis at gmail dot com...
>
> <quote>
>
> Be aware of oddities when dealing with 0 (zero) values in an array...
>
> This script:
> <?php
> $array = array('testing',0,'name');
> var_dump($array);
> //this will return true
> var_dump(in_array('foo', $array));
> //this will return false
> var_dump(in_array('foo', $array, TRUE));
> ?>
>
> It seems in non strict mode, the 0 value in the array is evaluating to
> boolean FALSE and in_array returns TRUE. Use strict mode to work around this
> peculiarity.
> This only seems to occur when there is an integer 0 in the array. A string
> '0' will return FALSE for the first test above (at least in 5.2.6).
>
> </quote>
>
> So use strict mode and this problem will go away. Oh, and please read the
> manual before asking a question in future.
>
> -Stut
I wouldn't consider it weird; it's just how PHP handles loose type
comparisons. I would certainly agree that it's not terribly obvious
why it happens, though. :) That said, it's consistent with PHP
behaviour.
James Ellis almost got it right in his note. As I already noted, it's
not because of a conversion to boolean FALSE, but a conversion to
integer 0. You can test this by substituting FALSE for the 0 in the
array in the example and trying it.
Torben
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