PHP中round()函數(shù)對浮點數(shù)進行四舍五入的方法

更新時間：2014年11月19日 10:09:28 投稿：shichen2014

這篇文章主要介紹了PHP中round()函數(shù)對浮點數(shù)進行四舍五入的方法,通過詳盡的實例對round()函數(shù)的各種常見用法進行了歸納整理,是非常實用的技巧,需要的朋友可以參考下

本文實例講述了PHP中round()函數(shù)對浮點數(shù)進行四舍五入的方法。分享給大家供大家參考。具體方法如下：

語法:round(x,prec)

參數(shù)	描述
x	可選,規(guī)定要舍入的數(shù)字.
prec	可選,規(guī)定小數(shù)點后的位數(shù).

說明:返回將 x 根據(jù)指定精度 prec(十進制小數(shù)點后數(shù)字的數(shù)目)進行四舍五入的結(jié)果,prec 也可以是負數(shù)或零(默認值).

提示和注釋

注釋:php默認不能正確處理類似 "12,300.2" 的字符串.

注釋:prec 參數(shù)是在 php 4 中被引入的,實例代碼如下:

復(fù)制代碼代碼如下:

<?php 

*/ 

echo round(3.4);         //輸出3 

echo "<br>"; 

echo round(3.5);         //輸出4 

echo "<br>"; 

echo round(3.6);         //輸出4 

echo "<br>"; 

echo round(3.6,0);         //輸出4 

echo "<br>"; 

echo round(1.95583,2);        //輸出1.96 

echo "<br>"; 

echo round(1241757,-3);        //輸出1242000 

echo "<br>"; 

echo round(4.045,2);         //輸出4.05 

echo "<br>"; 

echo round(4.055,2);         //輸出4.06 

//使用stdround函數(shù)代替php的round函數(shù) 

?>

復(fù)制代碼代碼如下:

<?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)= ".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 "; 

?>