Why does the following code:
System.out.println((int)(19.99 * 100));
produce the result “1998”?
Why does the following code: System.out.println((int)(19.99 * 100)); produce the result 1998?
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Why does the following code:
System.out.println((int)(19.99 * 100));
produce the result “1998”?
Rounding errors. If you look at the result of your calculation without the cast, you get:
So when you cast to int, the decimal part is dropped, not rounded up, and you get 1998.
The moral is, if you need an exact answer, don’t use float / double at all. If you’re talking about a discrete value like money, use int and deal with the atomic unit (eg. pence.) If you do need exact decimals, then
BigDecimalis your friend.While you can bodge the result here using
Math.round()to bring the result to where it’s expected, this won’t work in all cases and fails to address the underlying issue.