The program should crash, but it succeeds.

Integer division by zero is undefined behavior in C++. What happens may vary by compiler, compiler settings, operating system, processor, and such. It's better not to rely on any particular actual behavior and instead avoid it -- in this case by checking if the divisor is zero and only doing the division if it is non-zero.

The "Arithmetic operators" page on cppreference.com has some discussion in the "Multiplicative operators" section:

https://en.cppreference.com/w/cpp/language/operator_arithmetic

Edit: spelling