How to make the division of 2 ints produce a float instead of another int?

Question

In another Bruce Eckels exercise in calculating velocity, v = s / t where s and t are integers. How do I make it so the division cranks out a float?

Answer 1

Try:

v = (float)s / (float)t;

Casting the ints to floats will allow floating-point division to take place.

You really only need to cast one, though.

Answer 2

Just cast one of the two operands to a float first.

v = (float)s / t;

The cast has higher precedence than the division, so happens before the division.

The other operand will be effectively automatically cast to a float by the compiler because the rules say that if either operand is of floating point type then the operation will be a floating point operation, even if the other operand is integral. Java Language Specification, §4.2.4 and §15.17

Answer 3

You can cast the numerator or the denominator to float...

int operations usually return int, so you have to change one of the operanding numbers.

Answer 4

You can cast even just one of them, but for consistency you may want to explicitly cast both so something like v = (float)s / (float)t should work.

Answer 5

To lessen the impact on code readabilty, I'd suggest:

v = 1d* s/t;

Answer 6

Cast one of the integers to a float to force the operation to be done with floating point math. Otherwise integer math is always preferred. So:

v = (float)s / t;