PHP中round()函數對浮點數進行四舍五入的方法

2024-05-04 23:27:38

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這篇文章主要介紹了PHP中round()函數對浮點數進行四舍五入的方法,通過詳盡的實例對round()函數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()函數對浮點數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	描述
x	可選,規定要舍入的數字.
prec	可選,規定小數點后的位數.

說明:返回將 x 根據指定精度 prec(十進制小數點后數字的數目)進行四舍五入的結果,prec 也可以是負數或零(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 參數是在 php 4 中被引入的,實例代碼如下:

復制代碼代碼如下:

		<?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函數代替php的round函數 
		?>

復制代碼代碼如下:

		<?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 "; 
		?>