php - My function doesn't modify the array -

I wrote a function that changes an index array value on the left. It looks like:

  function index_shift ($ array, $ index) {$ n = count ($ array) - 1; ($ I = $ n; $ i & gt; = $ index; $ i -) $ $ array [$ i + 1] = $ array [$ i]; } Print_r ($ array); } $ Array_one = array ("A", "B", "C", "D", "E", "F", "G"); Index_shift ($ array_one, 3); Echo "
"; Print_r ($ array_one); I put the first  print_r  in the function to see if it works. This does, indicates that the values ​​have been moved to the left ( D  is on the fourth and fifth index, all values ​​are taken). But the second  print_r  outside the function shows that the array is not modified. It looks like a function works, but it does not modify the array. Maybe I'm   & amp;   should be used?   
 
 
 You are passing an array. If you want to modify the array, then you have to pass the reference of the array:  
  function index_shift (& $ array, $ index) {$ n = count ($ array) - 1; ($ I = $ n; $ i & gt; = $ index; $ i -) $ $ array [$ i + 1] = $ array [$ i]; } Print_r ($ array); }   
 Here is a link about context through context & amp;: