Program to toggle 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 0, then set it to 1 and if it is 1 then set it to 0.

Examples:

Input: N = 5, K = 2
Output: 7
5 is represented as 101 in binary
and has its second bit 0, so toggling
it will result in 111 i.e. 7.

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

Approach:

• Since XOR of unset and set bit results in a set bit and XOR of a set and set bit results in an unset bit. Hence performing bitwise XOR of any bit with a set bit results in toggle of that bit, i.e.

Any bit <bitwise XOR> Set bit = Toggle

which means,
0 ^ 1 = 1
1 ^ 1 = 0

• So in order to toggle a bit, performing a bitwise XOR 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++

// C++ program to toggle K-th bit of a number N
#include<bits/stdc++.h>
using namespace std;

// Function to toggle the kth bit of n
int toggleBit(int n, int k)
{
    return (n ^ (1 << (k - 1)));
}

// Driver code
int main()
{
    int n = 5, k = 2;
    cout << toggleBit(n, k) << endl;

    return 0;
}

// This code is contributed by noob2000

C

// C program to toggle K-th bit of a number N

#include <stdio.h>

// Function to toggle the kth bit of n
int toggleBit(int n, int k)
{
    return (n ^ (1 << (k - 1)));
}

// Driver code
int main()
{
    int n = 5, k = 2;

    printf("%d\n", toggleBit(n, k));

    return 0;
}

Java

// Java program to toggle K-th bit of a number N
class GFG
{

// Function to toggle the kth bit of n
static int toggleBit(int n, int k)
{
    return (n ^ (1 << (k - 1)));
}

// Driver code
public static void main(String []args)
{
    int n = 5, k = 2;

    System.out.printf("%d\n", toggleBit(n, k));
}
}

// This code is contributed by Rajput-Ji

Python3

# Python3 program to clear K-th bit
# of a number N

# Function to toggle the kth bit of n
def toggleBit(n, k) :

    return (n ^ (1 << (k - 1)));

# Driver code
if __name__ == "__main__" :

    n = 5; k = 2;

    print(toggleBit(n, k));

# This code is contributed by AnkitRai01

C#

// C# program to toggle K-th bit of a number N
using System;

class GFG
{

// Function to toggle the kth bit of n
static int toggleBit(int n, int k)
{
    return (n ^ (1 << (k - 1)));
}

// Driver code
public static void Main(String []args)
{
    int n = 5, k = 2;

    Console.WriteLine("{0}", toggleBit(n, k));
}
}

// This code is contributed by PrinciRaj1992

Javascript

<script>

// Javascript program to toggle K-th bit of a number N

// Function to toggle the kth bit of n
function toggleBit(n, k)
{
    return (n ^ (1 << (k - 1)));
}

// Driver code
var n = 5, k = 2;
document.write( toggleBit(n, k));

// This code is contributed by famously.
</script>

Output:

7

Time Complexity: O(1)

Auxiliary Space: O(1)