random number from -9 to 9 in C++

Question

just wondering, if I have the following code:

int randomNum = rand() % 18 + (-9);

will this create a random number from -9 to 9?

Answer 1

No, it won't. You're looking for:

int randomNum = rand() % 19 + (-9);

There are 19 distinct integers between -9 and +9 (including both), but rand() % 18 only gives 18 possibilities. This is why you need to use rand() % 19.