System.out.println(1/10) prints 0? [duplicate]

Question

Possible Duplicate:
Why the result of 1/3=0 in java?

I'm working with java, and part of my code requires a number to be divided by 10. To simplify (and show my question) I just put it into a println:

System.out.println(1/10);

that prints out 0. So, logically, I figured it was casting it to an int, so I tried

System.out.println((double)1/10);

and that printed out the proper 0.1. I don't understand why it automatically cast it into an int the first time though. Where else does it do this? Why?

Answer 1

1 is an int and 10 is an int and when you do int/int you get an int.

If you do 1.0/10 or 1/10.0 or 1.0/10.0 you will get a double as 0.1

IMHO: I think int/int should be a double which you can cast an int if you want integer division. i.e.

I would have

 a/b          // does double division
 (int)(a/b)   // does integer division.

instead you have to write

 a/b          // does integer division
 (double) a/b // does double division

Answer 2

It doesn't cast to int, it already is int. int / int is int.

Also note that when you cast to double as in (double)1/10, since the cast operator has higher precedence than division, this is the same as ((double)1)/10, which has the effect of causing the division to happen in double.

If you cast after division as in (double)(1/10), the result will be 0.0 .