PHP中round()函数对浮点数进行四舍五入的方法

本文实例讲述了PHP中round()函数对浮点数进行四舍五入的方法。分享给大家供大家参考。具体方法如下：

语法:round(x,prec)

说明:返回将 x 根据指定精度 prec(十进制小数点后数字的数目)进行四舍五入的结果,prec 也可以是负数或零(默认值).

提示和注释

注释:PHP 默认不能正确处理类似 "12,300.2" 的字符串.

注释:prec 参数是在 PHP 4 中被引入的,实例代码如下:

PHP */ echo round(3.4); //输出3 echo "
"; echo round(3.5); //输出4 echo "
"; echo round(3.6); //输出4 echo "
"; echo round(3.6,0); //输出4 echo "
"; echo round(1.95583,2); //输出1.96 echo "
"; echo round(1241757,-3); //输出1242000 echo "
"; echo round(4.045,2); //输出4.05 echo "
"; echo round(4.055,2); //输出4.06

//使用stdround函数代替PHP的round函数
?>

<div class="codetitle"><a style="CURSOR: pointer" data="52931" class="copybut" id="copybut52931" onclick="doCopy('code52931')"> 代码如下:<div class="codebody" id="code52931"><?php
function stdround($num,$d=0)
{
return round($num + 0.0001 / pow(10,$d),$d);
}

echo "round(1.005,2)= ".round(1.005,2). "n ";
echo "round(1.015,2)= ".round(1.015,2). "n ";
echo "round(1.025,2)= ".round(1.025,2). "n ";
echo "round(1.035,2)= ".round(1.035,2). "n ";
echo "round(1.045,2)= ".round(1.045,2). "n ";
echo "round(1.055,2)= ".round(1.055,2). "n ";
echo "round(1.065,2)= ".round(1.065,2). "n ";
echo "round(1.075,2)= ".round(1.075,2). "n ";
echo "round(1.085,2)= ".round(1.085,2). "n ";
echo "round(1.095,2)= ".round(1.095,2). "n ";

echo "stdround(1.005,2)= ".stdround(1.005,2). "n ";
echo "stdround(1.015,2)= ".stdround(1.015,2). "n ";
echo "stdround(1.025,2)= ".stdround(1.025,2). "n ";
echo "stdround(1.035,2)= ".stdround(1.035,2). "n ";
echo "stdround(1.045,2)= ".stdround(1.045,2). "n ";
echo "stdround(1.055,2)= ".stdround(1.055,2). "n ";
echo "stdround(1.065,2)= ".stdround(1.065,2). "n ";
echo "stdround(1.075,2)= ".stdround(1.075,2). "n ";
echo "stdround(1.085,2)= ".stdround(1.085,2). "n ";
echo "stdround(1.095,2)= ".stdround(1.095,2). "n ";

$m=0.000000000000001;
echo "n ";
echo "round(1.005+{$m},2)= ".round(1.005+$m,2). "n ";
echo "round(1.015+{$m},2)= ".round(1.015+$m,2). "n ";
echo "round(1.025+{$m},2)= ".round(1.025+$m,2). "n ";
echo "round(1.035+{$m},2)= ".round(1.035+$m,2). "n ";
echo "round(1.045+{$m},2)= ".round(1.045+$m,2). "n ";
echo "round(1.055+{$m},2)= ".round(1.055+$m,2). "n ";
echo "round(1.065+{$m},2)= ".round(1.065+$m,2). "n ";
echo "round(1.075+{$m},2)= ".round(1.075+$m,2). "n ";
echo "round(1.085+{$m},2)= ".round(1.085+$m,2). "n ";
echo "round(1.095+{$m},2)= ".round(1.095+$m,2). "n ";

echo "round(1.005,2). "n ";
?>

希望本文所述对大家的PHP程序设计有所帮助。

PHP round()函数函数函数四舍五入四舍五入四舍五入浮点数浮点数浮点数