problem with closure in preg_replace_callback

Question

This script check every line of some text for "FIRST" and "LAST" words, and trying to replace them by entries in $temp_names array.

$temp_names = array('FIRST' => array('John','Jack'),'LAST' => array('Doe','Smith'));

for ($i=0; $i < count($lines); $i++)
{ 
  $lines[$i] = preg_replace_callback("/FIRST|LAST/",
                                        function($matches) use ($temp_names){ 
                                        return array_shift($temp_names[$matches[0]]); }, $lines[$i]);

}

i have problem with return array_shift() in closure function. It correctly returns the first entry, but the entry stays in array. So every time it return "John" and "Doe". Why is that?

thanks.

Answer 1

In order to have any changes to the $temp_names array (such as shifting a value), you need to use it by reference like

function ($matches) use (&$temp_names)