zen-cart中的截取字符串的函数

////
// Truncate a string
  function zen_trunc_string($str = "", $len = 150, $more = 'true') {
    if ($str == "") return $str;
    if (is_array($str)) return $str;
    $str = trim($str);
    // if it's les than the size given, then return it
    if (strlen($str) <= $len) return $str;
    // else get that size of text
    $str = substr($str, 0, $len);
    // backtrack to the end of a word
    if ($str != "") {
      // check to see if there are any spaces left
      if (!substr_count($str , " ")) {
        if ($more == 'true') $str .= "...";
        return $str;
      }
      // backtrack
      while(strlen($str) && ($str[strlen($str)-1] != " ")) {
        $str = substr($str, 0, -1);
      }
      $str = substr($str, 0, -1);
      if ($more == 'true') $str .= "...";
      if ($more != 'true' and $more != 'false') $str .= $more;
    }
    return $str;
  }