Only variables should be passed by reference

I get this error on my admin controller and I'm not sure how to fix it. 

Severity: Runtime Notice
Message: Only variables should be passed by reference
Filename: controllers/Admin.php
Line Number: 14

Line 14: 

PHP Code:

$section = end($this->uri->segment_array()); 


Check the PHP documentation about the end() function: http://php.net/manual/en/function.end.php

Quoting the parameters section:

array
The array. This array is passed by reference because it is modified by the function. This means you must pass it a real variable and not a function returning an array because only actual variables may be passed by reference.

Try this:

PHP Code:

$segments = $this->uri->segment_array(); 

$section = end($segments); 


Best regards,
José Postiga
Senior Backend Developer