php浮点数高精度计算库

round($number, $decimals);
        //切割数字和小数点部分
        $sepList = explode(".", $item);
        $float = "";
        $integer = array_shift($sepList);
        if(count($sepList) > 0) {
            $float = implode("", $sepList);
        }

        $len = strlen($integer);
        if($len <= 3){
            return $item;
        }

        $newNumber = preg_replace_callback("/(\d{1,3})(?=(\d{3})+(?:$|\D))/", "self::merge_number", $integer);
        return $newNumber . "." . $float;
    }

    private function merge_number(array $matches) {
        return $matches[1].",";
    }
}