c++ - What happens when you bit shift beyond the end of a variable? -

if have variable (on stack) , left or right bit shift beyond end happens?

i.e.

byte x = 1; x >> n; 

what if x pointer memory cast byte , same thing?

byte* x = obtain pointer somewhere; *x = 1; *x >> n; 

it not (necessarily) become zero. behavior undefined (c99 §6.5.7, "bitwise shift operators"):

if value of right operand negative or greater or equal width of promoted left operand, behavior undefined.

(c++0x §5.8, "shift operators"):

the behavior undefined if right operand negative, or greater or equal length in bits of promoted left operand.

the storage of value being shifted has no effect on of this.