$num = 10.45678;
//第一种：利用round()对浮点数进行四舍五入
echo round($num,2); //10.46
//第二种：利用sprintf格式化字符串
$format_num = sprintf("%.2f",$num);
echo $format_num; //10.46
//第三种：利用千位分组来格式化数字的函数number_format()
echo number_format($num, 2); //10.46
//或者如下
echo number_format($num, 2, '.', ''); //10/46
破罐子互摔
