(PHP 4 = 4.0.5)
Searches haystack for
needle and returns the key
if it is found in the array,
FALSE otherwise.
注: Prior to PHP 4.2.0, array_search() returns NULL on failure instead of FALSE.
If the optional third parameter
strict is set to
TRUE then the array_search()
will also check the types of the
needle in the
haystack.
See also array_keys() and
in_array().