PHP function for counting words in a string

Here is a very useful code for counting the no of words in a string, ready to run and it will work in all situations.
If you find any problem with this function plz let me know.

<?
function count_words($str){
     $words = 0;
     $str = eregi_replace(" +", " ", $str);
     $array = explode(" ", $str);
     for($i=0;$i < count($array);$i++)
      {
         if (eregi("[0-9A-Za-zÀ-ÖØ-öø-ÿ]", $array[$i]))
             $words++;
     }
     return $words;
 }
 echo count_words('This is the second one , it will count wrong as well" , it will count 12 instead of 11 because the comma is counted too.');
 ?>