Java Bitwise Operators Double an int value 5 to 10 without using arithmetic operator or function in Java

Question

We would like to double an int value without using arithmetic operator or function in Java.

For example, we would like to double value 2 to 4, and 4 to 8.

And we cannot use * or + or Math.pow() function. 



// Left shifting as a quick way to multiply by 2.
public class Main {
  public static void main(String args[]) {
    
    int num = 5;

    num = num << 1;
    System.out.println(num);
    
    num = num << 1;
    System.out.println(num);
    
    num = num << 1;
    System.out.println(num);
  }
}

Note

Since each left shift has the effect of doubling the original value, we can use left shift as a way to multiply by 2.

If you shift a 1 bit into the high-order position (bit 31 for int or 63 for long), the value will become negative.




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