/**
 * php数字千分位格式化输出
 * @param $num
 * @return string
 */
function doFormatMoney($num)
{
    $tmp_num = strrev($num);
    $format_num = "";
    for ($i = 3; $i < strlen($num); $i += 3) {
        $format_num .= substr($tmp_num, 0, 3) . ",";
        $tmp_num = substr($tmp_num, 3);
    }
    $format_num .= $tmp_num;
    return strrev($format_num);
}

echo doFormatMoney(100000000);

echo number_format(100000000,0,'.',',');