Double arithmetic giving false result

Asked Jun 05 '14 at 16:43

Active Jun 05 '14 at 16:49

Viewed 44 times

I don't know why this code below is giving me "no". I tried to cast -0.2 to double and still getting "no"? What is the problem and how to fix it?

double d = -4;

double d1= -4.2;

if (d1== (d-0.2))
    cout<< "yes"<<endl;
else
    cout <<"no"<<endl;

edited Jun 05 '14 at 16:49

timrau

asked Jun 05 '14 at 16:43

Mariya

5

[What every developer needs to know about floating point](http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html) – Mooing Duck Jun 05 '14 at 16:45
1

http://www.smbc-comics.com/index.php?db=comics&id=2999#comic ([Not mine](http://stackoverflow.com/questions/588004/is-floating-point-math-broken)) – chris Jun 05 '14 at 16:45
I don't see the rounding error though: http://coliru.stacked-crooked.com/a/95f99c83bab5e5b5 – Mooing Duck Jun 05 '14 at 16:49
http://www.parashift.com/c++-faq/floating-point-arith.html – PaulMcKenzie Jun 05 '14 at 16:52
N-hundredth duplicate about "floating-point math broken" on SO – phuclv Jun 05 '14 at 16:54
Ok, thank you all , didn't know that it was floating problem. – Mariya Jun 05 '14 at 21:48

0 Answers0