Check whether K-th bit is set or not

Given a number n, check if k-th bit of n is set or not.

Examples:

Input : n = 5, k = 1
Output : SET
5 is represented as 101 in binary
and has its first bit set.

Input : n = 2, k = 3
Output : NOT SET
2 is represented as 10 in binary, 
all higher i.e. beyond MSB,
bits are NOT SET.

Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

Method 1 (Using Left Shift Operator)
Below are simple steps to find value of k-th bit

1) Left shift given number 1 by k-1 to create 
   a number that has only set bit as k-th bit.
    temp = 1 << (k-1)
2) If bitwise AND of n and temp is non-zero, 
   then result is SET else result is NOT SET.

Example:

 n = 75 and k = 4
 temp = 1 << (k-1) = 1 << 3 = 8 
 Binary Representation of temp = 0..00001000 
 Binary Representation of n = 0..01001011 
 Since bitwise AND of n and temp is non-zero,
 result is SET.

C++

// CPP program to check if k-th bit 
// of a given number is set or not 
#include <iostream> 
using namespace std; 
  
void isKthBitSet(int n, int k) 
{ 
    if (n & (1 << (k - 1))) 
        cout << "SET"; 
    else
        cout << "NOT SET"; 
} 
  
// Driver code 
int main() 
{ 
    int n = 5, k = 1; 
    isKthBitSet(n, k); 
    return 0; 
} 

Java

// Java program to check if k-th bit 
// of a given number is set or not 
  
class Number { 
    public static void isKthBitSet(int n, 
                                   int k) 
    { 
        if ((n & (1 << (k - 1))) == 1) 
            System.out.print("SET"); 
        else
            System.out.print("NOT SET"); 
    } 
  
    // driver code 
    public static void main(String[] args) 
    { 
        int n = 5, k = 1; 
        isKthBitSet(n, k); 
    } 
} 
  
// This code is contributed by rishabh_jain 

Python3

# Python3 code to check if k-th bit 
# of a given number is set or not 
  
def isKthBitSet(n, k): 
    if n & (1 << (k - 1)): 
        print( "SET") 
    else: 
        print("NOT SET") 
  
# Driver code 
n = 5
k = 1
isKthBitSet(n, k) 
  
# This code is contributed by "Sharad_Bhardwaj". 

C#

// C# program to check if k-th bit 
// of a given number is set or not. 
using System; 
  
class GFG { 
  
    public static void isKthBitSet(int n, 
                                   int k) 
    { 
        if ((n & (1 << (k - 1))) == 1) 
            Console.Write("SET"); 
        else
            Console.Write("NOT SET"); 
    } 
  
    // Driver code 
    public static void Main() 
    { 
        int n = 5, k = 1; 
  
        isKthBitSet(n, k); 
    } 
} 
  
// This code is contributed by nitin mittal. 

PHP

<?php 
// PHP program to check if  
// k-th bit of a given  
// number is set or not 
function isKthBitSet($n, $k) 
{ 
    if ($n & (1 << ($k - 1))) 
        echo "SET"; 
    else
        echo "NOT SET"; 
} 
  
// Driver code 
$n = 5; $k = 1; 
isKthBitSet($n, $k); 
  
// This code is contributed  
// by akt_mit 
?> 

Output:

SET

Method 2 (Using Right Shift Operator)
If we right shift n by k-1, we get last bit as 1 if k-th bit is set else 0.

C++

// CPP program to check if k-th bit 
// of a given number is set or not using 
// right shift operator. 
#include <iostream> 
using namespace std; 
  
void isKthBitSet(int n, int k) 
{ 
    if ((n >> (k - 1)) & 1) 
        cout << "SET"; 
    else
        cout << "NOT SET"; 
} 
  
// Driver code 
int main() 
{ 
    int n = 5, k = 1; 
    isKthBitSet(n, k); 
    return 0; 
} 

Java

// Java program to check if  
// k-th bit of a given number  
// is set or not using right  
// shift operator. 
import java.io.*; 
  
class GFG  
{ 
static void isKthBitSet(int n,  
                        int k) 
{ 
    if (((n >> (k - 1)) & 
               1) == 1) 
        System.out.println("SET"); 
    else
        System.out.println("NOT SET"); 
} 
  
// Driver code 
public static void main (String[] args)  
{ 
    int n = 5, k = 1; 
    isKthBitSet(n, k); 
} 
} 
  
// This code is contributed 
// by ajit 

Python3

# PHP program to check if k-th bit of  
# a given number is set or not using 
# right shift operator.  
  
def isKthBitSet(n, k):  
    if ((n >> (k - 1)) and 1): 
        print("SET") 
    else: 
        print("NOT SET")  
  
# Driver code  
n, k = 5, 1
isKthBitSet(n, k)  
  
# This code contributed by  
# PrinciRaj1992 

C#

// C# program to check if  
// k-th bit of a given number  
// is set or not using right  
// shift operator 
using System; 
  
class GFG 
{ 
static void isKthBitSet(int n,  
                        int k) 
{ 
    if (((n >> (k - 1)) & 
              1) == 1) 
        Console.WriteLine("SET"); 
    else
        Console.WriteLine("NOT SET"); 
} 
  
// Driver code 
static public void Main () 
{ 
    int n = 5, k = 1; 
    isKthBitSet(n, k); 
} 
} 
  
// This code is contributed 
// by ajit 

PHP

<?php 
// PHP program to check  
// if k-th bit of a given  
// number is set or not  
// using right shift operator. 
  
function isKthBitSet($n, $k) 
{ 
    if (($n >> ($k - 1)) & 1) 
        echo "SET"; 
    else
        echo "NOT SET"; 
} 
  
// Driver code 
$n = 5; $k = 1; 
isKthBitSet($n, $k); 
  
// This code is contributed  
// by akt_mit 
?> 

Output:

SET

This article is contributed by SAKSHI TIWARI. If you like GeeksforGeeks(We know you do!) and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

My Personal Notes

Suggest a Topic

Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

C++

Java

Python3

C#

PHP

C++

Java

Python3

C#

PHP

Recommended Posts: