Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

Double number Rounding issue

Posted on 2004-03-24
6
Medium Priority
?
183 Views
Last Modified: 2010-04-01
Hi Experts,

Look at the simple example

double a = 1440.0;
double b = 0.06;
double c = a * b;

out.println("Result " + c)  gives 86.39999999999999;

Where
out.println("Result " + 1440.0 * 0.06) gives exact value 86.4   which is correct;

Does anybody knows why this happens, and how to fix a*b -> 86.4


Thanks
Britto
0
Comment
Question by:de_britto
  • 2
6 Comments
 
LVL 28

Accepted Solution

by:
rrz earned 100 total points
ID: 10672181
>out.println("Result " + 1440.0 * 0.06) gives exact value 86.4   which is correct;
I don't get that result on my Tomcat 5 and  JDK1.4 .  I get   86.39999999999999  

>how to fix a*b -> 86.4
Here is one way.  

<%
float a = 1440.0f;
float b = 0.06f;
float c = a * b;
out.println("Float Result = " + c);  
%>
0
 
LVL 92

Assisted Solution

by:objects
objects earned 100 total points
ID: 10674232
Use DecimalFormat class to display to the number of required decuimal places.


DecimalFormat df = new DecimalFormat("#.##");
out.println("Result "+df.format(c));  
0
 
LVL 9

Expert Comment

by:mmuruganandam
ID: 10674601
DecimalFormat format = new DecimalFormat("#.#");
out.println(format.format(c));            
0
 
LVL 28

Expert Comment

by:rrz
ID: 10678566
to objects and mmuruganandam,  
Great, your solutions work for the given values, because DecimalFormat uses half-even rounding  for formatting.  

 "de britto" wanted the  exact value
>gives exact value 86.4   which is correct  

But what if the variables change ?  (  b = 0.061111 for example )  
How could your solution be applied to the general case ?  

0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

How to fix a SonicWall Gateway Anti-Virus firewall blocking automatic updates to apps like Windows, Adobe, Symantec, etc.
Hello there! As a developer I have modified and refactored the unit tests which was written by fellow developers in the past. On the course, I have gone through various misconceptions and technical challenges when it comes to implementation. I would…
Integration Management Part 2
This lesson discusses how to use a Mainform + Subforms in Microsoft Access to find and enter data for payments on orders. The sample data comes from a custom shop that builds and sells movable storage structures that are delivered to your property. …
Suggested Courses

971 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question