Question

What is 1.#INF and why does casting to a float or double prevent a division by 0 of crashing?
Also, any great ideas of how to prevent division by 0? (Like any macro or template)?

int nQuota = 0;

int nZero = 3 / nQuota; //crash
cout << nZero << endl;

float fZero = 2 / nQuota; //crash
cout << fZero << endl;

if I use instead:

int nZero = 3 / (float)nQuota;
cout << nZero << endl;
//Output = -2147483648

float fZero = 2 / (float)nQuota;
cout << fZero << endl;
//Output = 1.#INF

Answer 1

1.#INF is positive infinity. You will get it when you divide a positive float by zero (if you divide the float zero itself by zero, then the result will be “not a number”).

On the other hand, if you divide an integer by zero, the program will crash.

The reason float fZero = 2 / nQuota; crashes is because both operands of the / operator are integers, so the division is performed on integers. It doesn’t matter that you then store the result in a float; C++ has no notion of target typing.

Why positive infinity cast to an integer is the smallest integer, I have no idea.