integer-overflow

问题 How does Java handle integer underflows and overflows? Leading on from that, how would you check/test that this is occurring? 回答1: If it overflows, it goes back to the minimum value and continues from there. If it underflows, it goes back to the maximum value and continues from there. You can check that beforehand as follows: public static boolean willAdditionOverflow(int left, int right) { if (right < 0 && right != Integer.MIN_VALUE) { return willSubtractionOverflow(left, -right); } else {

问题 I was writing a program in C++ to find all solutions of a b = c , where a , b and c together use all the digits 0-9 exactly once. The program looped over values of a and b , and it ran a digit-counting routine each time on a , b and a b to check if the digits condition was satisfied. However, spurious solutions can be generated when a b overflows the integer limit. I ended up checking for this using code like: unsigned long b, c, c_test; ... c_test=c*b; // Possible overflow if (c_test/b != c)

问题 I often see questions relating to Overflow errors with vba. My question is why use the integer variable declaration instead of just defining all numerical variables (excluding double etc.) as long ? Unless you\'re performing an operation like in a for loop where you can guarantee that the value won\'t exceed the 32,767 limit, is there an impact on performance or something else that would dictate not using long ? 回答1: Integer variables are stored as 16-bit (2-byte) numbers msdn Long (long