Program to clear K-th bit of a number N

Given a number N, the task is to clear the K-th bit of this number N. If K-th bit is 1, then clear it to 0 and if it is 0 then leave it unchanged.

Examples:

Input: N = 5, K = 1
Output: 4
5 is represented as 101 in binary
and has its first bit 1, so clearing
it will result in 100 i.e. 4.

Input: N = 5, K = 2
Output: 5
5 is represented as 101 in binary
and has its second bit is already 0,
so clearing it will result in 101 i.e. 5.

Approach:

  • Since bitwise AND of any bit with a reset bit results in a reset bit, i.e.
    Any bit <bitwise AND> Reset bit = Reset bit
    
    which means,
    0 & 0 = 0
    1 & 0 = 0
    
  • So for clearing a bit, performing a bitwise AND of the number with a reset bit is the best idea.
    n = n & ~(1 << k)
    OR
    n &= ~(1 << k)
    
    where k is the bit that is to be cleared
    

Below is the implementation of the above approach:

C

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// C program to clear K-th bit of a number N
  
#include <stdio.h>
  
// Function to clear the kth bit of n
int clearBit(int n, int k)
{
    return (n & (~(1 << (k - 1))));
}
  
// Driver code
int main()
{
    int n = 5, k = 1;
  
    printf("%d\n", clearBit(n, k));
  
    return 0;
}

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Python3

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# Python3 program to clear
# K-th bit of a number N
  
# Function to clear the kth bit of n
def clearBit(n, k):
    return (n & ( ~(1 << (k - 1))))
  
# Driver code
n = 5
k = 1
  
print(clearBit(n, k))
  
# This code is contributed 
# by Mohit Kumar

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Java

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// Java program to clear K-th bit of a number N 
class GFG 
{
      
    // Function to clear the kth bit of n 
    static int clearBit(int n, int k) 
    
        return (n & (~(1 << (k - 1)))); 
    
      
    // Driver code 
    public static void main (String[] args) 
    
        int n = 5, k = 1
      
        System.out.println(clearBit(n, k)); 
    
}
  
// This code is contributed by AnkitRai01

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C#

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// C# program to clear K-th bit of a number N 
using System;
  
class GFG 
{
      
    // Function to clear the kth bit of n 
    static int clearBit(int n, int k) 
    
        return (n & (~(1 << (k - 1)))); 
    
      
    // Driver code 
    public static void Main (String[] args) 
    
        int n = 5, k = 1; 
      
        Console.WriteLine(clearBit(n, k)); 
    
}
  
// This code is contributed by PrinciRaj1992

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Output:

4

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