PHP's strcasecmp behaving strangely

Question

The PHP code below

$input1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$input2 = array("a" => "GREEN", "B" => "brown", "yellow", "RED");

$result = array_intersect_uassoc($input1, $input2, "strcasecmp");
print_r($result);

Is returning value

Array ( [b] => brown )

Am wondering since strcasecmp is case insensitive, why is "green" and "Green" not considered as matching.

Answer 1

Your misunderstanding isn't with strcasecmp, it's with array_intersect_uassoc. The last argument is not used to compare the values, it's used to compare the keys.

Therefore, the case insensitive check is not on the value, it's on the key itself which is why the "b" and "B" indexes intersect.