left operand
right operand
set if an overflow occurs, is not affected otherwise
the product
bool overflow; assert(muls(2, 3, overflow) == 6); assert(!overflow); assert(muls(-200, 300, overflow) == -60_000); assert(!overflow); assert(muls(1, int.max, overflow) == int.max); assert(!overflow); assert(muls(int.min, 1, overflow) == int.min); assert(!overflow); assert(muls(int.max, 2, overflow) == (int.max * 2)); assert(overflow); overflow = false; assert(muls(int.min, -1, overflow) == int.min); assert(overflow); assert(muls(0, 0, overflow) == 0); assert(overflow); // sticky
bool overflow; assert(muls(2L, 3L, overflow) == 6); assert(!overflow); assert(muls(-200L, 300L, overflow) == -60_000); assert(!overflow); assert(muls(1, long.max, overflow) == long.max); assert(!overflow); assert(muls(long.min, 1L, overflow) == long.min); assert(!overflow); assert(muls(long.max, 2L, overflow) == (long.max * 2)); assert(overflow); overflow = false; assert(muls(-1L, long.min, overflow) == long.min); assert(overflow); overflow = false; assert(muls(long.min, -1L, overflow) == long.min); assert(overflow); assert(muls(0L, 0L, overflow) == 0); assert(overflow); // sticky
Multiply 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.