Re: in_array breaks down for 0 as value

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On Thu, 2008-11-20 at 09:25 +0000, Stut wrote:
> 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
> 
> -- 
> http://stut.net/
> 
What about using the === and !== comparisons to compare and make sure
that 0 is not giving a false false.


Ash
www.ashleysheridan.co.uk


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