Bit Manipulation |Get Bit | Set Bit | Update Bit | Lecture 14

Java - Introduction to Programming

Lecture 14

Bit Manipulation

Get Bit

import java.util.*;

 

public class Bits {

   public static void main(String args[]) {

      int n = 5; //0101

      int pos = 3;

      int bitMask = 1<<pos;

 

      if((bitMask & n) == 0) {

          System.out.println("bit was zero");

      } else {

          System.out.println("bit was one");

      }

   }

}

 

Set Bit

import java.util.*;

 

public class Bits {

   public static void main(String args[]) {

      int n = 5; //0101

      int pos = 1;

      int bitMask = 1<<pos;

 

      int newNumber = bitMask | n;

      System.out.println(newNumber);

   }

}

Clear Bit

import java.util.*;

public class Bits {

  public static void main(String args[]) {

     int n = 5; //0101

     int pos = 2;

     int bitMask = 1<<pos;

     int newBitMask = ~(bitMask);

     int newNumber = newBitMask & n;

     System.out.println(newNumber);

  }

}

 

Update Bit

import java.util.*;

 

public class Bits {

   public static void main(String args[]) {

       Scanner sc = new Scanner(System.in);

       int oper = sc.nextInt();

       // oper=1 -> set; oper=0 -> clear

      int n = 5;

      int pos = 1;

     

      int bitMask = 1<<pos;

      if(oper == 1) {

          //set

          int newNumber = bitMask | n;

          System.out.println(newNumber);

      } else {

       //clear

       int newBitMask = ~(bitMask);

       int newNumber = newBitMask & n;

       System.out.println(newNumber);

      }

     

   }

}

 

Homework Problems

1. Write a program to find if a number is a power of 2 or not.

2. Write a program to toggle a bit a position = “pos” in a number “n”.

3. Write a program to count the number of 1’s in a binary representation of the number.

4. Write 2 functions => decimalToBinary() & binaryToDecimal() to convert a number from one number system to another. [BONUS]