2's compliment

[Arun Prasath]

How the 2's copmliment is performed while doing signed left shifting and
and arithmatic operations when number is in negative.?

say for example,
(in binary,)

int x=-1;

so x=1000 0000 0000 0000 0000 0000 0000 0001; (this is in binary, for
understanding,i know binary cannot be input)

x=x>>30;

here x is printed as -1. why and how is this?

[Jesper de Jong]

Well, -1 is not 1000 ... 0001, it is all 1's.

So you have x = 1111 1111 1111 1111 1111 1111 1111 1111 (binary) and you shift right with sign extension - all the bits will still be 1's, and the result is still -1.

The pattern 1000 ... 0001 is -2147483647, not -1.

Two's complement
[ July 31, 2006: Message edited by: Jesper Young ]

[Campbell Ritchie]

,i know binary cannot be input

Yes it can.

x=Integer.parseInt("1000 0000 0000 0000 0000 0000 0000 0001", 2);
System.out.println(x);

OR

x = myScanner.nextInt(2);//enter "1000 0000 0000 0000 0000 0000 0000 0001"

CR