PHP Array as index without array - php

Question

I have a PHP Script which works quite fine except that I get this error Message
Undefined index: Array in [...]/exp.php on line 239
On this line there is this code:
$out_kostenstelle = $kostenstellen[$nextShift["kostenstelle"]][1].
"(".$nextShift["kostenstelle"].")";
I think the only part where an Array as an Index can occur ist the part where $nextShift["kostenstelle"] is the index for $kostenstellen.
However when I try to catch this part (it is in a loop with many hundred runs so I can not manually check it) with this code, my script never enters the part inside the if clause
if(is_array($nextShift["kostenstelle"]))
{
echo "<pre>";
var_dump($nextShift);
echo "</pre>";
die();
}
This does not make any sense to me and I tried many things. without success.
I think this might be enough of the code where the error could be but just in case here are the structure of $kostenstellen and $nextShift
Kostenstellen:
array(2) {
[100]=>
array(2) {
[0]=>
string(3) "100"
[1]=>
string(11) "Company A"
}
[200]=>
array(2) {
[0]=>
string(3) "300"
[1]=>
string(12) "Company B"
}
}
and nextShift:
array(4) {
["id"]=>
string(2) "168"
["start_unix"]=>
string(10) "1466780000"
["end_unix"]=>
string(10) "1466812400"
["kostenstelle"]=>
string(3) "100"
}

Answer 1

There's no way around it: the problem is that the index you're trying to use is itself an array.
When you access an array in php, $array[$index], PHP will try to stringify it if it's not already a string or numeric. Stringifying an array gives the literal "Array"; like you have here.
However, there's another possibility: that when you run your loop, the array was stringified already. It means someplace before, someone casted it to a string.
You could check if with such an if:
if(is_array($nextShift["kostenstelle"]) || $nextShift["kostenstelle"] == "Array")
{
echo "<pre>";
var_dump($nextShift);
echo "</pre>";
die();
}