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What is the problem with 'double'?

Posted on 2004-04-12
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Medium Priority
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Last Modified: 2010-03-31
Here I attach the code segment and it output:

Code:

public static void main(String args[]){
    for(double d = 1; d >= 0; d -= 0.2){
        System.out.println(d);
    }
}

Output:

1.0
0.8
0.6000000000000001
0.4000000000000001
0.20000000000000007
5.551115123125783E-17

Why is this happened? and How to solve this problem if I am expecting the output of:

1.0
0.8
0.6
0.4
0.2
0.0

Thank You.
0
Comment
Question by:b612_forever
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5 Comments
 
LVL 15

Assisted Solution

by:Javatm
Javatm earned 80 total points
ID: 10810092
This should solve your problem :

public static void main(String args[]) {

    DecimalFormat d1 = new DecimalFormat("0.0");

    for(double d = 1; d >= 0; d -= 0.2) {
    System.out.println(d1.format(d));
    }
}

Hope that helps . . .
Javatm
0
 
LVL 30

Assisted Solution

by:Mayank S
Mayank S earned 80 total points
ID: 10810540
Well, precision-related matters always come into picture while dealing with floats and sometimes also with doubles. You should never look for or compare exact values but keep a margin for error-tolerance while dealing with them.
0
 
LVL 24

Accepted Solution

by:
sciuriware earned 80 total points
ID: 10810805
Remember that a computer is binary organised: many floating numbers can't be represented in float or double
like PI in the decimal system.
;JOOP!
0
 
LVL 1

Author Comment

by:b612_forever
ID: 10810958
Since Javatm provide the solution and mayankeagle,scuriware provide the explanation, I add 10 point for this question and split it to three.
0
 
LVL 30

Expert Comment

by:Mayank S
ID: 10810991
Glad to help ;-)
0

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