Bitwise Operators - Different Output ?

Question

Hello !
Can anyone please as to why these two different programs are giving different values ? Both are using Right
Shift Operator >>> .
The first shifts right the value a set to -1 to 24 bit positions giving a = 255 . But with the second program
doing the same in a loop we start getting zero from the 9 iteration and continues till 24 ( and onwards ) . Why
are we not getting the same value for a from the two programs ?
// Right Unsigned Shifting : >>> ( Shift Right zero fill )
class RUnsignShift {
public static void main(String args[]) {
int a = - 1 , b = 0 ;
System.out.println("\nDemonstration : Right shift zero fill Operator >>> ");
System.out.print("Original value int a = " + a +" ") ;
System.out.println("Bit pattern : 11111111 11111111 11111111 11111111");
b = a ;
a = a >>> 24 ;
System.out.print("a = -1 >>> 24 (Zero-fill) bit positions a = " + a +" ");
System.out.println("Bit pattern : 00000000 00000000 00000000 11111111");
b = b >> 24 ;
System.out.print("b = -1 >> 24 (Sign Ext.) 24 bit positions b = " + b +"\n");
SECOND PROGRAM
class RUnsignShift2 {
public static void main(String args[]) {
int a = -1 , i ;
System.out.println("Demonstration : Right shift zero fill Operator >>> ");
System.out.print("Original value int a = " + a +" ") ;
System.out.println("Bit pattern : 11111111 11111111 11111111 11111111");
for(i = 0 ; i < 10 ; i++) {
a = a >>> i ;
System.out.println("a >>> " + i + " (Zero-fill) bit positions a = " + a +" ");
//System.out.println("Bit pattern : 00000000 00000000 00000000 11111111");
}

Answer 1

NADEEMUDDIN wrote:
a = a >>> 24 ;
SECOND PROGRAM
for(i = 0 ; i < 10 ; i++) {
a = a >>> i ;
System.out.println("a >>> " + i + " (Zero-fill) bit positions a = " + a +" ");
//System.out.println("Bit pattern : 00000000 00000000 00000000 11111111");
}The problem is that in your second program, a gets shifted with i meaning first time is a >>> 0, second time a >>> 1 etc. and all that it's equivalent with a >>> 45 at the end of the loop.
To have the same results some changes must occur:
for(i = 0 ; i < 24 ; i++) {
a = a >>> 1 ;
System.out.println("a >>> " + i + " (Zero-fill) bit positions a = " + a +" ");
//System.out.println("Bit pattern : 00000000 00000000 00000000 11111111");
}So in the final pass (24th) the a = a >>> 24.
Cheers!