PHP: testing for existence of a cell in a multidimensional array

I was having the same problem, except i needed it for some Drupal stuff. I also needed to check if objects contained items as well as arrays. Here's the code I made, its a recursive search that looks to see if objects contain the value as well as arrays. Thought someone might find it useful.

function recursiveIsset($variable, $checkArray, $i=0) {
    $new_var = null;
    if(is_array($variable) && array_key_exists($checkArray[$i], $variable))
        $new_var = $variable[$checkArray[$i]];
    else if(is_object($variable) && array_key_exists($checkArray[$i], $variable))
        $new_var = $variable->$checkArray[$i];
    if(!isset($new_var))
        return false;

    else if(count($checkArray) > $i + 1)
        return recursiveIsset($new_var, $checkArray, $i+1);
    else
        return $new_var;
}

Use: For instance

recursiveIsset($variables, array('content', 'body', '#object', 'body', 'und'))

In my case in drupal this ment for me that the following variable existed

$variables['content']['body']['#object']->body['und']

due note that just because '#object' is called object does not mean that it is. My recursive search also would return true if this location existed

$variables->content->body['#object']->body['und']

isset() is the cannonical method of testing, even for multidimensional arrays. Unless you need to know exactly which dimension is missing, then something like

isset($arr[1][2][3])

is perfectly acceptable, even if the [1] and [2] elements aren't there (3 can't exist unless 1 and 2 are there).

However, if you have

$arr['a'] = null;

then

isset($arr['a']); // false
array_key_exists('a', $arr); // true

comment followup:

Maybe this analogy will help. Think of a PHP variable (an actual variable, an array element, etc...) as a cardboard box:

• isset() looks inside the box and figures out if the box's contents can be typecast to something that's "not null". It doesn't care if the box exists or not - it only cares about the box's contents. If the box doesn't exist, then it obviously can't contain anything.
• array_key_exists() checks if the box itself exists or not. The contents of the box are irrelevant, it's checking for traces of cardboard.