Question

I have a PHP array.

array
  0 => int 1
  1 => int 13
  2 => int 16
  3 => int 17
  4 => int 18

What I want returned is a new array like this:

array(1, 13, 16, 17, 18)

ie. The values are now keys of a new array

I’ve tried array_flip, but I need to drop the values.
I’ve googled around and there doesn’t seem to anything that relates.

If someone could point me to the right direction or provide a better solution, it would be much appreciated.

EDIT:

array_flip returns:

array
  1 => int 0
  13 => int 1
  16 => int 2
  17 => int 3
  18 => int 4

What I want is just: array(1, 13, 16, 17, 18).

Am I understanding this wrong? Does the output I want actually have null values on each key?

Answer 1

You seem to not understand how arrays work. Every array that contains at least one value always has a key(s) and a value(s). In the case of this:

array(1, 13, 16, 17, 18)

the values are 1,13,16,… and the keys are implicitly set by PHP. In this case the value 1 has a key 0, value 13 has a key 1 and so on.

The only difference between your first and second array is that in the first you have keys defined explicitly. In short, the arrays are identical.