Common array functions in php (5) (obtain the set of key names in the array) and array key names

Common array functions in php (5) (obtain the set of key names in the array) and array key names
Array_keys ($ arr, $ search_value, $ strict );

-- Obtains the set of key names in the array.

// The array to be retrieved in parameter 1; the default value of the key to be retrieved in parameter 2 is NULL; and the default value of parameter 3 is false if it is strictly compared (=. Parameter 3 is added in php5.0.

$ Arr1 = array ('A' => 'apple', 'B' => 'bana', 'F' => false, 'b1 '=> false, 'b2' => false, 'b3' => 'false', 'b4 '=> true, 'num1' => 1, 'num2' => '1 '); // var_dump (array_keys ($ arr1, 'Banana '); var_dump (array_keys ($ arr1, 1, false ));

Output: array (3) {[0] => string (2) "b4" [1] => string (4) "num1" [2] => string (4) "num2 "}

There is no strict comparison. The true value of the index 'b4 'is also treated as 1.