Positive integers that multiply to a negative value

Question

I am learning C++ by reading Stroustrup\'s \"Principles and Practice Using C++\".

In the section about pre- and post-conditions there is the following example of functio

Answer 1

No, there aren't any values that will, within the bounds of defined behavior of standard C++, violate the post-condition. However, there are values that still can make the function behave incorrectly, namely values so large that their product does not fit within an integer. Try passing 200'000 and 15'000.

Due to the way most compilers implement C++, you might see the post-condition being violated, but what you're actually observing is undefined behavior due to integer overflow.