left operand
right operand
set if an overflow occurs, is not affected otherwise
the sum
bool overflow; assert(adds(2, 3, overflow) == 5); assert(!overflow); assert(adds(1, int.max - 1, overflow) == int.max); assert(!overflow); assert(adds(int.min + 1, -1, overflow) == int.min); assert(!overflow); assert(adds(int.max, 1, overflow) == int.min); assert(overflow); overflow = false; assert(adds(int.min, -1, overflow) == int.max); assert(overflow); assert(adds(0, 0, overflow) == 0); assert(overflow); // sticky
bool overflow; assert(adds(2L, 3L, overflow) == 5); assert(!overflow); assert(adds(1L, long.max - 1, overflow) == long.max); assert(!overflow); assert(adds(long.min + 1, -1, overflow) == long.min); assert(!overflow); assert(adds(long.max, 1, overflow) == long.min); assert(overflow); overflow = false; assert(adds(long.min, -1, overflow) == long.max); assert(overflow); assert(adds(0L, 0L, overflow) == 0); assert(overflow); // sticky
Add two signed integers, checking for overflow.
The overflow is sticky, meaning a sequence of operations can be done and overflow need only be checked at the end.