Função de limitar string em php

Abaixo segue a função para limitar os caracteres!

<?php

 function str_chop($string, $length = 60, $center = false, $append = null){
     // Set the default append string
     if ($append === null)
         $append = ($center === true) ? ' ... ' : '...';

     // Get some measurements
     $len_string = strlen($string);
     $len_append = strlen($append);

     // If the string is longer than the maximum length, we need to chop it
     if ($len_string > $length) {
         // Check if we want to chop it in half
         if ($center === true) {
             // Get the lengths of each segment
             $len_start = $length / 2;
             $len_end = $len_start - $len_append;

             // Get each segment
             $seg_start = substr($string, 0, $len_start);
             $seg_end = substr($string, $len_string - $len_end, $len_end);

             // Stick them together
             $string = $seg_start.$append.$seg_end;
         } else {
             // Otherwise, just chop the end off
             $string = substr($string, 0, $length - $len_append).$append;
         }
     }

     return $string;
 }

?>

Referência: http://www.hardmob.com.br/programacao-and-desenvolvimento/379571-limitando-caracteres-php.html