Obviously, your result is overflow. Therefore, the part above 65536 in 4000000 is discarded, and only the lower 16 bits are kept. Therefore, the result is equivalent to: 4000000% 65536 = 2304.

As for why this happens, I guess, if you are sure that your C is a long type, it should be the compiler's problem. I have encountered this problem before when converting from char type to short type.

However, you can do this to be sure:

Long c;

c = a；

c = c * b； That's enough.

In addition, you can cast:

Long c;

C = (length) a* (length) b;