Question

I’m a C++ beginner 😉
How good is the code below as a way of finding all prime numbers between 2-1000:

int i, j;

for (i=2; i<1000; i++) {
  for (j=2; j<=(i/j); j++) {
    if (! (i%j))
      break;
    if (j > (i/j))
      cout << i << " is prime\n";
  }
}

Answer 1

The one simple answer to the whole bunch of text we posted up here is : Trial division!
If someone mentioned mathematical basis that this task was based on, we’d save plenty of time 😉