Generate Sortkey v.3

sortkey-v3.php

<?php 

function utf8_substr($str,$start)
{
   preg_match_all("/./u", $str, $ar);

   if(func_num_args() >= 3) {
       $end = func_get_arg(2);
       return join("",array_slice($ar[0],$start,$end));
   } else {
       return join("",array_slice($ar[0],$start));
   }
}

function string2sortkey($lemma){

 $charTable=array(
    'A' => 2,
  	'a' => 2,
  	'Ä' => 2,
  	'ä' => 2,
  	'B' => 3,
  	'b' => 3,
  	'C' => 4,
  	'c' => 4,
  	'D' => 5,
  	'd' => 5,
  	'E' => 6,
  	'e' => 6,
  	'F' => 7,
  	'f' => 7,
  	'G' => 8,
  	'g' => 8,
  	'H' => 9,
  	'h' => 9,
  	'I' => 10,
  	'i' => 10,
  	'J' => 11,
  	'j' => 11,
  	'K' => 12,
  	'k' => 12,
  	'L' => 13,
  	'l' => 13,
  	'M' => 14,
  	'm' => 14,
  	'N' => 15,
  	'n' => 15,
  	'O' => 16,
  	'o' => 16,
  	'Ö' => 16,
  	'ö' => 16,
  	'P' => 17,
  	'p' => 17,
  	'Q' => 18,
  	'q' => 18,
  	'R' => 19,
  	'r' => 19,
  	'S' => 20,
  	's' => 20,
  	'ß' => 20,
  	'T' => 21,
  	't' => 21,
  	'U' => 22,
  	'u' => 22,
  	'Ü' => 22,
  	'ü' => 22,
  	'V' => 23,
  	'v' => 23,
  	'W' => 24,
  	'w' => 24,
  	'X' => 25,
  	'x' => 25,
  	'Y' => 26,
  	'y' => 26,
  	'Z' => 27,
  	'z' => 27
  );

  $lemma=(string)$lemma;  

  print "String: ".$lemma."\n";

  $sort=0;
  $multiply=1000000;
  for($i=0;$i<4;$i++)
  {
	  $current = 0;
	  if(strlen($lemma)<=$i)
	  {
  	  //$title ist zu ende
	  }
	  else
	  {
	    $char = utf8_substr($lemma, $i, 1);
	    
  	  if(array_key_exists($char,$charTable))
  	  {
  	    print "[".$char."]";
	  	  $current=$charTable[$char];
  	  }
  	  else
  	  { print "[1]";
	  	  $current = 1;
  	  }
	  }
	  $current=$current*($multiply);
	  $multiply=$multiply/100;
	  $sort=$sort+$current;
  }
  return $sort;

}
print " ".string2sortkey("Überzeit")."\n";
print " ".string2sortkey("öffentlich-rechtlich")."\n";
print " ".string2sortkey("Außen")."\n";
print " ".string2sortkey("Augen")."\n";