# shift operators

sanjana narayanan

Ranch Hand

Posts: 142

posted 12 years ago

Hi,

I am not able to understand shift operators. Can someone help me..

Though i know the basics of left and right shift operators, i encounter the problem when it comes to the calculations.

Pl go thru the following code..

class BitShift {

public static void main(String [] args) {

int x = 0x80000000;

System.out.println("Before shift x equals " + x);

x = x >> 4;

System.out.println("After shift x equals " + x);

}

}

I think in the exam we are not allowed to use the calculators..So how do i know x=-2147483648 and after shift x=-134217728

-sanjana

I am not able to understand shift operators. Can someone help me..

Though i know the basics of left and right shift operators, i encounter the problem when it comes to the calculations.

Pl go thru the following code..

class BitShift {

public static void main(String [] args) {

int x = 0x80000000;

System.out.println("Before shift x equals " + x);

x = x >> 4;

System.out.println("After shift x equals " + x);

}

}

I think in the exam we are not allowed to use the calculators..So how do i know x=-2147483648 and after shift x=-134217728

-sanjana

Vad Fogel

Ranch Hand

Posts: 504

posted 12 years ago

You're not up to doing excessively laborious calculations on the exam, just stick to what's covered in K&B, they've done an awesome job about it. All you need to understand is how the shifting works in general, when the sign changes, and when the result remains the same. Also, make sure you're familiar with shifting by negative numbers and how implicit conversion applies to the operands. In your example, what's worth knowing is that 0x80000000 represents Integer.MIN_VALUE, you're right-shifting it by 4, so the sign stays negative, and the result will be Integer.MIN_VALUE/16.