Division by zero: int vs. float

Question

Dividing an int by zero, will throw an exception, but a float won\'t - at least in Java. Why does a float have additional NaN info, while an int type doesn\'t?

Answer 1

Ints and floats are represented differently inside the machine. Integers usually use a signed, two's complement representation that is (essentially) the number written out in base two. Floats, on the other hand, use a more complex representation that can hold much larger and much smaller values. However, the machine reserves several special bit patterns for floats to mean things other than numbers. There's values for NaN, and for positive or negative infinity, for example. This means that if you divide a float by zero, there is a series of bits that the computer can use to encode that you divided by zero. For ints, all bit patterns are used to encode numbers, so there's no meaningful series of bits the computer could use to represent the error.

This isn't an essential property of ints, though. One could, in theory, make an integer representation that handles division by zero by returning some NaN variant. It's just not what's done in practice.