array_search not finding string? - php

Question

$className = "Class B: Wednesday 6pm";
// $studentArray is multidimensional array with student info
foreach($studentArray as $student) {
echo array_search($className,$student);
}
// Contents of $student is
Array
(
[Groups] => 187,267
[Birthday] => DateTime Object
(
[date] => 1981-02-04 00:00:00.000000
[timezone_type] => 3
[timezone] => UTC
)
[_IGTestScore] => 0
[Email] => blank#blank.com
[_IGClass1] => Class B: Wednesday 6pm
[_IGAttendedClass1] => DateTime Object
(
[date] => 2016-02-17 00:00:00.000000
[timezone_type] => 3
[timezone] => UTC
)
[FirstName] => Joe
[Id] => 3
[LastName] => Schmoe
)
The output of that is:
_IGTestScore
If I do a var_dump on $className and $student['_IGClass1] I get:
string(22) "Class B: Wednesday 6pm"
string(22) "Class B: Wednesday 6pm"
Never had an issue with array_search before, but this has been driving me crazy, and can't seem to figure out what is going on here. It seems that any string search is coming out the same. But if I do a search for an integer, like 3, it will pull out "Id" correctly.
UPDATE - whole multi-dimensional array
Array
(
[0] => Array
(
[Groups] => 187,267
[Birthday] => DateTime Object
(
[date] => 1981-02-04 00:00:00.000000
[timezone_type] => 3
[timezone] => UTC
)
[_IGTestScore] => 0
[Email] => blank#blank.com
[_IGClass1] => Class B: Wednesday 6pm
[_IGAttendedClass1] => DateTime Object
(
[date] => 2016-02-17 00:00:00.000000
[timezone_type] => 3
[timezone] => UTC
)
[FirstName] => Joe
[Id] => 3
[LastName] => Schmoe
)
)

Answer 1

I have found the problem... but I don't know the reason: for me, it is a mystery!
The problem is _IGTestScore as integer: if _IGTestScore is an integer, array_search() returns _IGTestScore ( In fact it returns _IGTestScore for any searchstring, even if they doesn't exists! ), if _IGTestScore is set to '0' (string) or to a positive integer, array_search() returns correct value!
It's a bug?
Someone have an explanation?
Edit:
Obviously, there is a solution: use the “strict” parameter:
array_search( $className, $student, True );
But... Why “Class B: Wednesday 6pm” == 0?