Why 2.3 - 1.2 = 1.0999 ?

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Tried with float and double - same result. Please help.

Posted 28-Jan-14 19:54pm

Member 10545052

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2 solutions

Solution 2

It's a fact of life with floats and doubles etc. (decimals are better).

Read this for the why : http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html[^]

Posted 28-Jan-14 20:51pm

Mehdi Gholam

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Member 10545052 29-Jan-14 3:05am

Not helped - same problem :(

CPallini 29-Jan-14 3:07am

5.

Mehdi Gholam 29-Jan-14 3:09am

Cheers!

Member 10545052 29-Jan-14 3:13am

Clear. It works correctly only with strings:
new BigDecimal(operand_a + "") instead
new BigDecimal(operand_a)

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skydger · Accepted Answer · 2014-01-28T20:50:00

Solution 1

Hello.
An issue is Java uses IEEE 754[^] standard. Consider not to use float, use double instead. When one uses floating point numbers he should be careful.
For further details please see What Every Computer Scientist Should Know About Floating-Point Arithmetic[^]
As for your question... You should use some round operations or to manipulate values with help of BigDecimal[^] or something like that.

Java

BigDecimal a = new BigDecimal("2.3");
BigDecimal b = new BigDecimal("1.2");
BigDecimal c = a.subtract(b);

Please follow this link[^] for other cases.
Good luck.

Posted 28-Jan-14 20:50pm

skydger

Comments

Member 10545052 29-Jan-14 3:05am

Not helped - same problem :(

CPallini 29-Jan-14 3:07am

5.

Member 10545052 29-Jan-14 3:12am

Clear. It works correctly only with strings:
new BigDecimal(operand_a + "") instead
new BigDecimal(operand_a)

skydger 29-Jan-14 3:32am

Well, it works with doubles too if to use MathContext in constructor:
MathContext mc = new MathContext(2, RoundingMode.HALF_UP)
BigDecimal a = new BigDecimal(2.3d, mc);

http://docs.oracle.com/javase/1.5.0/docs/api/java/math/MathContext.html

skydger 29-Jan-14 3:27am

Thank you :)