How to find all substrings of a string in PHP

Question

I need to convert strings of the form

\"a b c\"

into arrays of the form

Array
(
    [0] => a
    [1] => a b
    [2] =         


        

Answer 1

This works and it works also with multibyte strings, all the methods above don't, they return null and duplicated values.

function substrings($str, $charset = 'UTF-8') {   
  $length = mb_strlen($str, $charset);

  $subs = [];
  for ($i = 0; $i < $length; $i++)
    for ($j = 1; $j <= $length; $j++)
      $subs[] = mb_substr($str, $i, $j, $charset);

  return array_unique($subs);
}

print_r(substrings("php"));