左移操作

Question

1. When I execute j <<= 1 while j is initially zero, it ends up as a zero instead of 1 as it normally should be. Any other initial value is normally doubled.

   Does anyone know why this is happening?

2. Why bitwise operations on slice fields cause runtime errors?

Answer 1

Consider j = 0:

0000 0000 0000 0000

Now what is j <<= 1? It's:

0000 0000 0000 0000
←                 ↑
Shifted         Added

Which is.. the same number (0).

Left shifting a number by 1, is multiplying it by 2, 0*2 is 0.