I noticed the following strange occurrence:
var_dump(in_array("test", array_keys(array("hello"))));
Yields: bool(true)
How is this possible? Array does not contains keys, therefore array_keys() will return an empty array. Test is not in this empty array, so why would it return true? Is this a bug in PHP?
simple answer: loose typing, 'test' == 0
Use
var_dump(in_array("test", array_keys(array("hello")), true));
for strict typing
And all arrays have keys, if you don't explicitly assign a key, then PHP will assign one based on incrementing integers from 0 (hence 'test' == 0).... array_keys() will not be empty, because PHP will assign a key of 0 to your array entry of "hello"
array_keys(array("hello")))is[0], it's not empty.