PHP：array_search返回null

Question

I have a regular array that contains numbers from 1 to 14 that is generated by retrieving INTs from a SQL result column.

Using another query I'm returning another INT.

I'm searching for this INT in my array.

$key = array_search("$roomNb", $freeRooms);

However when I try to echo this key nothing appears. It is empty.

If I echo $freeRooms using a loop I get:

1
2
3
4
5
6
7
8
9
10
11
12
14

If I echo $roomNb I get

5

So I can't understand why I'm not getting anything in return. I should be expecting a key of 4 no? What could be causing this?

Answer 1

Most likely $key is false which when sent to echo will appear as nothing. Instead you should use var_dump to determine the value of $key

False is returned from array_search when the needle is not found

Null is only returned when the parameters you pass to array_search are invalid

http://php.net/manual/en/function.array-search.php

Test this code here using http://writecodeonline.com/php/:

echo false;
echo null;
var_dump(false);
var_dump(null);

$code = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14);
$roomNb = 5;

var_dump(array_search("$roomNb", $code));

Should work just fine. echo will output nothing. var_dump will output stuff. And the key is found at 4.