shift operator question

[Chitra Jay]

Given a variable x of type int(which may contain a negative value) which are correct ways of doubling the value of x,barring any overflow?
(a) x << 1;
(b) x <<= 1;
The answer is (b).
Can anybody please explain why?? i thought both are correct.
Thanks

[geetha nagarajan]

a.)x << 1:The value is not assigned back to x,after shifting.
b.)x <<=1 :It's actually : x=x<<1.
So,after shifting,the value is assigned back to x.
Am i right?

[Chitra Jay]

Can anybody please explain this with an example?

[Corey McGlone]

Originally posted by Chitra Jay:
Can anybody please explain this with an example?

Just write a program, compile it, and execute it. That will tell you what happens. Try this:

int x = 2;
System.out.println(x);
x << 1;
System.out.println(x);
x <<= 1;
System.out.println(x);

What's the result? If you don't understand why you get the results that you get, please ask.
Corey

[Junilu Lacar]

Don't know what else you're looking for. Would this help?

void foo() {
   int x = 2;
   System.out.println("x << 1 => " + (x << 1) + ", x => " + x);
   System.out.println("x <<= 1 => " + (x <<= 1) + ", x => " + x);
}

Junilu

[Chitra Jay]

Oops!! Forgot the concept that the value of the left-hand operand is NOT affected by the shift operator ,whereas in the second case,x gets the new value due to extended assignment..Yeah I got it!! Thanks a lot for your examples..