Array copy values to keys in PHP [duplicate]

Question

I have this array:

$a = array('b', 'c', 'd'); 

Is there a simple method to convert the array to the following?

$a = array('b' => 'b', 'c' => 'c', 'd' => 'd'); 

Answer 1

$final_array = array_combine($a, $a); 

Reference: http://php.net/array-combine

P.S. Be careful with source array containing duplicated keys like the following:

$a = ['one','two','one']; 

Note the duplicated one element.