C ++逻辑语句

Question

I am a grader for a C++ class. My skills in the more advanced concepts are pretty lacking overall due to lack of practice, so I am not familiar with the ins-and-outs of the language. My question is about a block of code with an unusual line in an assignment about dice rolls.

#include <iostream>

using namespace std;

int main()
{
   int numSims = numSims % 12 == 0 || numSims > 1000;
   //Other irrelevant code follows
}

I can't find anything saying this is bad syntax. I can't see why a student would want to do this when this kind of statement, as far as I know, can't execute. Is there a hidden secret here than I'm missing?

Answer 1

This will execute but with an uninitialized numSims value when the expression on the right is evaluated. At the end numSims will end up with either a 0 or a 1.

Edit

Taking into account all the discussion in the comments below, this is technically Undefined Behavior that can result in the program crashing on some hardware platforms. (It is also possible, but unlikely, for it to fire phasors or reverse the polarity of the neutron flow - depending on your hardware platform.)

On many systems in use today, the program will run and that undefined behavior (which results from trying to use the indeterminate value stored in the uninitialized numSims variable) will result in numSims ending up with either a 0 or 1.