在coldfusion9下用round和numberformat做四舍五入不可靠

最新推荐文章于 2022-10-20 11:50:47 发布

原创最新推荐文章于 2022-10-20 11:50:47 发布 · 1k 阅读

0 ·

CC 4.0 BY-SA版权

本文探讨了特定数值下浮点数运算与四舍五入处理的差异，通过实例展示了直接乘法与四舍五入操作可能导致的结果不同，并提供了解决方案。

round(2619.615*100)的结果是不等于round(261961.5)

下面是演示代码：

<cfoutput>round(2619.615)=#round(2619.615)#</cfoutput><br/>
<cfoutput>round(261961.4)=#round(261961.4)#</cfoutput><br/>
<cfoutput>round(261961.5)=#round(261961.5)#</cfoutput><br/>
<cfoutput>round(261961.6)=#round(261961.6)#</cfoutput><br/>
<cfoutput>2619.615*100=#2619.615*100#</cfoutput><br/>
<cfoutput>round(2619.614*100)=#round(2619.614*100)#</cfoutput><br/>
<cfoutput>round(2619.615*100)=#round(2619.615*100)#</cfoutput><br/>
<cfoutput>round(2619.616*100)=#round(2619.616*100)#</cfoutput><br/>
<cfoutput>round(2619.615*100)/100=#round(2619.615*100)/100#</cfoutput><br/>
<cfoutput>numberformat(2619.615,0.00)=#numberformat(2619.615,0.00)#</cfoutput><br/>
<cfoutput>numberformat(2619.615*100,0.00)=#numberformat(2619.615*100,0.00)#</cfoutput><br/>
<cfoutput>numberformat(2619.614*100,0)=#numberformat(2619.614*100,0)#</cfoutput><br/>
<cfoutput>numberformat(2619.615*100,0)=#numberformat(2619.615*100,0)#</cfoutput><br/>
<cfoutput>numberformat(2619.616*100,0)=#numberformat(2619.616*100,0)#</cfoutput><br/>
<cfoutput>numberformat(261961.4,0)=#numberformat(261961.4,0)#</cfoutput><br/>
<cfoutput>numberformat(261961.5,0)=#numberformat(261961.5,0)#</cfoutput><br/>
<cfoutput>numberformat(261961.6,0)=#numberformat(261961.6,0)#</cfoutput><br/>

<cfoutput>Round(961.5)=#Round(961.5)#</cfoutput><br/>
<cfoutput>Round(9.615*100)=#Round(9.615*100)#</cfoutput><br/>
<cfoutput>Round(1961.5)=#Round(1961.5)#</cfoutput><br/>
<cfoutput>Round(19.615*100)=#Round(19.615*100)#</cfoutput><br/>
<cfoutput>Round(21961.5)=#Round(21961.5)#</cfoutput><br/>
<cfoutput>Round(219.615*100)=#Round(219.615*100)#</cfoutput><br/>
<cfoutput>Round(321961.5)=#Round(321961.5)#</cfoutput><br/>
<cfoutput>Round(3219.615*100)=#Round(3219.615*100)#</cfoutput><br/>
<cfoutput>Round(4321961.5)=#Round(4321961.5)#</cfoutput><br/>
<cfoutput>Round(43219.615*100)=#Round(43219.615*100)#</cfoutput><br/>

<cfset a=2619.615*100>
<cfoutput>a=2619.615*100=#a#</cfoutput><br/>
<cfoutput>round(a)=#round(a)#</cfoutput><br/>
<cfset b=261961.5>
<cfoutput>b=#b#</cfoutput><br/>
<cfoutput>round(b)=#round(b)#</cfoutput><br/>

结果

round(2619.615)=2620
round(261961.4)=261961
round(261961.5)=261962
round(261961.6)=261962
2619.615*100=261961.5
round(2619.614*100)=261961
round(2619.615*100)=261961
round(2619.616*100)=261962
round(2619.615*100)/100=2619.61
numberformat(2619.615,0.00)=2619.62
numberformat(2619.615*100,0.00)=261961.50
numberformat(2619.614*100,0)=261961
numberformat(2619.615*100,0)=261961
numberformat(2619.616*100,0)=261962
numberformat(261961.4,0)=261961
numberformat(261961.5,0)=261962
numberformat(261961.6,0)=261962
Round(961.5)=962
Round(9.615*100)=962
Round(1961.5)=1962
Round(19.615*100)=1961
Round(21961.5)=21962
Round(219.615*100)=21962
Round(321961.5)=321962
Round(3219.615*100)=321962
Round(4321961.5)=4321962
Round(43219.615*100)=4321962
a=2619.615*100=261961.5
round(a)=261961
b=261961.5
round(b)=261962

原因：估计是程序优化的结果。

解决方法：&一个空字符串，再让它自动转换类型

<cfoutput>round(2619.615*100)=#round(2619.615*100)#</cfoutput><br/>
<cfoutput>round(261961.5)=#round(261961.5)#</cfoutput><br/>
<cfoutput>round(2619.615*100 & "")=#round(2619.615*100 & "")#</cfoutput><br/>

结果

round(2619.615*100)=261961
round(261961.5)=261962
round(2619.615*100 & "")=261962