Not calculating volume properly

Question

volume = (4/3 * PI) * (Math.Pow(5, 3));
return volume;

The code above should return 523.6 but it returns 392.7. I can't figure it out but its probably something stupid that I am missing. Changing it to be a double literal does not change the problem.

inavda · Accepted Answer · 2018-10-11T22:10:19.837

5

4 and 3 are both ints so dividing them will produce an int, 1. This is probably not the value you were expecting.

You have to cast the 4 to a double before computing the quotient with 3.

edited Oct 11 '18 at 22:10

answered Oct 11 '18 at 22:04

inavda

333
5
15

2

cast or make at least one of them a double literal, e.g. `4.0` – bolov Oct 11 '18 at 22:15

score 1 · Answer 2 · answered Oct 11 '18 at 22:41

1

You can also just change 4 to 4.0, since yes the issue is that it is a integer so something called Integer Division happens.

volume = (4.0/3.0 * PI) * (Math.Pow(5, 3));
return volume;

answered Oct 11 '18 at 22:41

cheriejw

364
3
13

Hamid Jolany · Answer 3 · 2020-12-05T17:19:44.470

-5

cast to double

double volume = (4.0 / 3.0 * Math.PI) * (Math.Pow(5, 3));

edited Dec 05 '20 at 17:19

answered Oct 11 '18 at 22:07

Hamid Jolany

800
7
11

4

This experiences the same problem because it calculates `4 / 3` using integer division. https://www.ideone.com/nyu3Xt – clcto Oct 11 '18 at 22:11

Not calculating volume properly

3 Answers3