How to cause an intentional division by zero?

Question

For testing reasons I would like to cause a division by zero in my C++ code. I wrote this code:

int x = 9;
cout << "int x=" << x;
int y = 10/(x-9);
y += 10;

I see "int =9" printed on the screen, but the application doesn't crash. Is it because of some compiler optimizations (I compile with gcc)? What could be the reason?

Answer 1

Make the variables volatile. Reads and writes to volatile variables are considered observable:

volatile x = 1;
volatile y = 0;
volatile z = x / y;

Answer 2

Because y is not being used, it's getting optimized away.
Try adding a cout << y at the end.

Alternatively, you can turn off optimization:

gcc -O0 file.cpp

Answer 3

Division by zero is an undefined behavior. Not crashing is also pretty much a proper subset of the potentially infinite number of possible behaviors in the domain of undefined behavior.