What's the best way to copy an array and keep the keys with empty values

Question

In PHP, what's the best way to copy an array and keep the keys with empty values?

array1 = array("apple" => "green", "banana" => "yellow);

I want to copy array1 to array2 and keep only the keys...

array2 = array("apple" => "", "banana" => "");

Answer 1

you can use foreach to produce a new array, or one of numerous array functions

Answer 2

return array_fill_keys(array_keys($array1), "");

(Example run: http://www.ideone.com/SuMt2)

Answer 3

What about array_keys(), it return an array that has the keys of another array as values.

You can then use array_flip() to change keys for values and voilá, you have your result.

In a nutshell:

$array2 = array_flip(array_keys($array1));