如何检查另一个数组中是否存在该数组键？

I'm using the CakePHP 2.0 framework and I'm facing one problem. It's giving me the following error. I also used array_key_exists.

: Undefined offset: 2 [APP/View/Doctors/admin_customize_plan_new.ctp, line 28]style="display:none"; id="checktab4">

I have two arrays. First is stored in $carePlansList:

Array
(
[0] => Array
    (
        [EveCarePlansList] => Array
            (
                [id] => 1
                [care_plan_name] => CHF
            )

    )

[1] => Array
    (
        [EveCarePlansList] => Array
            (
                [id] => 3
                [care_plan_name] => Hypertension
            )

    )

[2] => Array
    (
        [EveCarePlansList] => Array
            (
                [id] => 4
                [care_plan_name] => ABC
            )

    )
)

Second one is called $QuestionUserexists

Array
(
[0] => Array
    (
        [EveChfQuestionsUser] => Array
            (
                [cq_cp_id] => 1
            )

    )

[1] => Array
    (
        [EveChfQuestionsUser] => Array
            (
                [cq_cp_id] => 3
            )

    )

)

Now when I make a comparison between these two arrays, I'll get the error above.

My foreach loop is:

<?php 
foreach ($carePlansList as $key => $plansList) { ?>
    <li role="presentation" class="planLists" 
    <?php if($QuestionUserexists[$key]['EveChfQuestionsUser']['cq_cp_id'] == $plansList['EveCarePlansList']['id'] ){ 
        }else{?>
                style="display:none";
            <?php } ?>>
    </li>

add a check: isset()

foreach ($carePlansList as $key => $plansList) { ?>
<li role="presentation" class="planLists" 
<?php if(isset($QuestionUserexists[$key]) && 
$QuestionUserexists[$key]['EveChfQuestionsUser']['cq_cp_id'] == $plansList['EveCarePlansList']['id'] ){ 
    }else{?>
            style="display:none";
        <?php } ?>>
</li>
endforeach;