PHP array_key_exists returning FALSE incorrectly

Question

My data is being pulled from a client's CMS, but I'm getting strange results

print_r($appliance_data);
foreach ($appliance_data as $adKey => $adValue) {
    print_r($adKey);
    print_r($adValue);
    print_r(array_key_exists($adKey, $appliance_data));
    print_r(isset($appliance_data[$adKey]));
}

With output

Array
(
    [94] => stdClass Object
        (
            [operation] => 0
            [value] => 0
        )

    [102] => stdClass Object
        (
            [operation] => 501
            [value] => 4
        )

    [90] => stdClass Object
        (
            [operation] => 0
            [value] => 0
        )
)
94
stdClass Object
(
    [operation] => 0
    [value] => 0
)
(boolean) FALSE
(boolean) FALSE
102
stdClass Object
(
    [operation] => 501
    [value] => 4
)
(boolean) FALSE
(boolean) FALSE
90
stdClass Object
(
    [operation] => 0
    [value] => 0
)
(boolean) FALSE
(boolean) FALSE

Any idea what's causing this?

Edit: The error is that array_key_exists AND isset return FALSE for a key obtained by looping over an array!

serialize($appliance_data)



a:7:{s:2:"94";O:8:"stdClass":3:{s:9:"operation";s:3:"514";s:5:"value";s:1:"2";s:9:"frequency";s:1:"0";}s:3:"102";O:8:"stdClass":3:{s:9:"operation";s:3:"511";s:5:"value";s:1:"4";s:9:"frequency";s:1:"1";}s:2:"90";O:8:"stdClass":3:{s:9:"operation";s:1:"0";s:5:"value";s:1:"0";s:9:"frequency";s:1:"0";}s:2:"68";O:8:"stdClass":3:{s:9:"operation";s:3:"501";s:5:"value";s:1:"3";s:9:"frequency";s:1:"2";}s:2:"66";O:8:"stdClass":3:{s:9:"operation";s:1:"0";s:5:"value";s:1:"0";s:9:"frequency";s:1:"0";}s:2:"84";O:8:"stdClass":3:{s:9:"operation";s:1:"0";s:5:"value";s:1:"0";s:9:"frequency";s:1:"0";}s:2:"98";O:8:"stdClass":3:{s:9:"operation";s:1:"0";s:5:"value";s:1:"0";s:9:"frequency";s:1:"0";}}

Some of your code is odd (won't run as it is - too many brackets after print_r()). The loop bit looks like it ought to run fine, whereas the last line should cause an error. Can you confirm this by running it? I get the loop running fine when I try similar code. — Matt Gibson
– Matt Gibson, Commented Apr 4, 2012 at 9:37
@Matt, The extra bracket was due to the code being deep within a clients CMS. The array is provided by the client CMS, so I'm thinking its encoded incorrectly! — Zeophlite
– Zeophlite, Commented Apr 11, 2012 at 3:32

Matt Gibson · Accepted Answer · 2012-04-11 11:37:41Z

5

You are using a string '94' instead of an int 94. Try:

print_r(array_key_exists(94, $appliance_data));

Edit: I can't reproduce this locally at all - can anyone else?

I tried to replicate this with the following code:

$first = new stdClass();
$first->operation = 0;
$first->value = 0;
$second = new stdClass();
$second->operation = 501;
$second->value = 4;
$third = new stdClass();
$third->operation = 0;
$third->value = 0;

$appliance_data = array(94 => $first, 102 => $second, 90 => $third);
// Same output when using these lines too:
// $appliance_data = array('94' => $first, '102' => $second, '90' => $third);
// $appliance_data = array("94" => $first, "102" => $second, "90" => $third);

print_r($appliance_data);
echo "\n\n";
foreach ($appliance_data as $adKey => $adValue) {
    print_r($adKey);
    echo "\n";
    print_r($adValue);
    print_r(array_key_exists($adKey, $appliance_data));
    echo "\n";
    print_r(isset($appliance_data[$adKey]));
    echo "\n\n";
}

And got this output:

Array
(
    [94] => stdClass Object
        (
            [operation] => 0
            [value] => 0
        )

    [102] => stdClass Object
        (
            [operation] => 501
            [value] => 4
        )

    [90] => stdClass Object
        (
            [operation] => 0
            [value] => 0
        )

)


94
stdClass Object
(
    [operation] => 0
    [value] => 0
)
1
1

102
stdClass Object
(
    [operation] => 501
    [value] => 4
)
1
1

90
stdClass Object
(
    [operation] => 0
    [value] => 0
)
1
1

edited Apr 11, 2012 at 11:37

answered Apr 4, 2012 at 9:27

Matt Gibson

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10 Comments

benedict_w Over a year ago

It's not a string in the loop though?

Matt Gibson Over a year ago

Yes, the loop still looks weird.

Matt Gibson Over a year ago

I suspect this is not directly copy pasted, due to lines like print_r($adValue)); which has too many brackets.

benedict_w Over a year ago

Do you need to reset the array index when calling array_key_exists in a loop? What happens using isset()

Matt Gibson Over a year ago

Good catch: according to a comment on the man page here php.net/manual/en/function.array-key-exists.php by manhon824, you do need to call reset() first. I tried similar code however, and it worked for the loop structure.

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