operator n assignment

[pravin kumar]

What is the result that will be printed out here ?
int i = - 128;
System.out.println((byte)i << 1);

answer is -256 ..please explain how to calculate the same...

[Jay Pawar]

Originally posted by pravin kumar:
What is the result that will be printed out here ?
int i = - 128;
System.out.println((byte)i << 1);

answer is -256 ..please explain how to calculate the same...

-128 is represented as 1111 1111 1111 1111 1111 1111 1000 0000

when you perform (byte)i << 1 last 8 bits of i are considered which are 1000 0000
and then left shift operation is carried out. Now point to be noted here is whenever a bit operation is performed the number is represented as int (32 bit) so -128 is represented as
1111 1111 1111 1111 1111 1111 1000 0000 and then when you left shift by 1
you get
1111 1111 1111 1111 1111 1111 0000 0000 which is -256


There would be big difference in the answer if you try to print this
System.out.println((byte)(i<<1));

Hope that helps
[ December 10, 2005: Message edited by: Jay Pawar ]