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Toggling k-th bit of a number

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  • Difficulty Level : Easy
  • Last Updated : 31 May, 2022
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For a given number n, if k-th bit is 0, then toggle it to 1 and if it is 1 then, toggle it to 0.
Examples : 
 

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

Input : n = 2, k = 3
Output : 6

Input : n = 75, k = 4
Output : 67

 

Below are simple steps to find the 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) Return bitwise XOR of temp and n.  Since temp
   has only k-th bit set, doing XOR would toggle 
   only this bit.

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 
 Bitwise XOR of two numbers = 0..01000011

 

C++




// CPP program to toggle k-th bit of n
#include<iostream>
using namespace std;
 
int toggleKthBit(int n, int k)
{
    return (n ^ (1 << (k-1)));
}
 
// Driver code
int main()
{
    int n = 5, k = 1;
    cout << toggleKthBit(n , k);
    return 0;
}

Java




// Java program to toggle
// k-th bit of a number
 
class Toggle
{
    static int toggleKthBit(int n, int k)
    {
        return (n ^ (1 << (k-1)));
    }
     
    // main function
    public static void main (String[] args)
    {  
        int n = 5, k = 1;
        System.out.println(toggleKthBit(n , k));
    }
}

Python3




# Python3 code to toggle k-th bit of n
 
def toggleKthBit(n, k):
    return (n ^ (1 << (k-1)))
     
# Driver code
n = 5
k = 1
print( toggleKthBit(n , k))
 
# This code is contributed by "Sharad_Bhardwaj".

C#




// C# program to toggle
// k-th bit of a number
using System;
 
class GFG {
     
    static int toggleKthBit(int n, int k)
    {
        return (n ^ (1 << (k-1)));
    }
      
    // main function
    public static void Main()
    {  
        int n = 5, k = 1;
         
        Console.WriteLine(toggleKthBit(n , k));
    }
}
 
//This code is contributed by Anant Agarwal.

PHP




<?php
// Php program to toggle k-th bit of n
 
function toggleKthBit($n, $k)
{
    return ($n ^ (1 << ($k - 1)));
}
 
// Driver code
$n = 5;
$k = 1;
echo toggleKthBit($n, $k);
 
// This code is contributed by Ajit
?>

Javascript




<script>
 
    // Javascript program to toggle
    // k-th bit of a number
     
    function toggleKthBit(n, k)
    {
        return (n ^ (1 << (k-1)));
    }
     
    let n = 5, k = 1;
           
      document.write(toggleKthBit(n , k));
     
</script>

Output :  

4

Time Complexity : O(1)

Space Complexity : O(1)

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 write.geeksforgeeks.org or mail your article to review-team@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.
 


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