Question

I wrote a simple divide function in C#:

    private string divide(int a, int b)
    {
        return string.Format("Result: {0}", a / b);
    }

Calling MessageBox.Show(divide(3, 0)) results in, as you would expect, a DivideByZeroException.

So I decided to typecast a into a float (to get a non-whole-number return value), like so:

    private string divide(int a, int b)
    {
        return string.Format("Result: {0}", (float)a / b);
    }

Oddly enough, this now shows me Result: Infinity.

This seems like a bug to me, although I could be mistaken. Is it because the result is now a float, and it’s seen as essentially the return value of 3 / 1 x 10^-99999 or something similar?

I’m quite flabbergasted at this result.

Answer 1

This is the behavior when you convert int to float. This has been taken from the MSDN documentation:

Dividing a floating-point value by zero will result in either positive
infinity, negative infinity, or Not-a-Number (NaN) according to the
rules of IEEE 754 arithmetic. Floating-point operations never throw an
exception. For more information, see Single and Double.