# How to turn off a particular bit in a number?

• Difficulty Level : Easy
• Last Updated : 26 May, 2022

Given a number n and a value k, turn off the k’th bit in n. Please note that k = 1 means the rightmost bit.
Examples:

```Input:  n = 15, k = 1
Output: 14

Input:  n = 14, k = 1
Output: 14
The rightmost bit was already off, so no change.

Input:  n = 15, k = 2
Output: 13

Input:  n = 15, k = 3
Output: 11

Input:  n = 15, k = 4
Output: 7

Input:  n = 15, k >= 5
Output: 15 ```

The idea is to use bitwise <<, & and ~ operators. Using expression “~(1 << (k – 1))“, we get a number which has all bits set, except the k’th bit. If we do bitwise & of this expression with n, we get a number which has all bits same as n except the k’th bit which is 0.
Below is the implementation of above idea.

## C++

 `#include ` `using` `namespace` `std;`   `// Returns a number that has all bits same as n` `// except the k'th bit which is made 0` `int` `turnOffK(``int` `n, ``int` `k)` `{` `    ``// k must be greater than 0` `    ``if` `(k <= 0) ``return` `n;`   `    ``// Do & of n with a number with all set bits except` `    ``// the k'th bit` `    ``return` `(n & ~(1 << (k - 1)));` `}`   `// Driver program to test above function` `int` `main()` `{` `    ``int` `n = 15;` `    ``int` `k = 4;` `    ``cout << turnOffK(n, k);` `    ``return` `0;` `}`

## Java

 `// Java program to turn off a particular bit in a number` `import` `java.io.*;`   `class` `TurnOff ` `{` `    ``// Function to returns a number that has all bits same as n` `    ``// except the k'th bit which is made 0` `    ``static` `int` `turnOffK(``int` `n, ``int` `k)` `    ``{` `        ``// k must be greater than 0` `        ``if` `(k <= ``0``) ` `            ``return` `n;` ` `  `        ``// Do & of n with a number with all set bits except` `        ``// the k'th bit` `        ``return` `(n & ~(``1` `<< (k - ``1``)));` `    ``}` `    `  `    ``// Driver program` `    ``public` `static` `void` `main (String[] args) ` `    ``{` `        ``int` `n = ``15``;` `        ``int` `k = ``4``;` `        ``System.out.println(turnOffK(n, k));` `    ``}` `}` `// Contributed by Pramod Kumar`

## Python3

 `# Returns a number that` `# has all bits same as n` `# except the k'th bit` `# which is made 0`   `def` `turnOffK(n,k):`   `    ``# k must be greater than 0` `    ``if` `(k <``=` `0``): ` `        ``return` `n` ` `  `    ``# Do & of n with a number` `    ``# with all set bits except` `    ``# the k'th bit` `    ``return` `(n & ~(``1` `<< (k ``-` `1``)))`   ` `  `# Driver code` `n ``=` `15` `k ``=` `4` `print``(turnOffK(n, k))`   `# This code is contributed` `# by Anant Agarwal.`

## C#

 `// C# program to turn off a ` `// particular bit in a number` `using` `System;`   `class` `GFG` `{` `    `  `    ``// Function to returns a number ` `    ``// that has all bits same as n` `    ``// except the k'th bit which is ` `    ``// made 0` `    ``static` `int` `turnOffK(``int` `n, ``int` `k)` `    ``{` `        ``// k must be greater than 0` `        ``if` `(k <= 0) ` `            ``return` `n;`   `        ``// Do & of n with a number ` `        ``// with all set bits except` `        ``// the k'th bit` `        ``return` `(n & ~ (1 << (k - 1)));` `    ``}` `    `  `    ``// Driver Code` `    ``public` `static` `void` `Main () ` `    ``{` `        ``int` `n = 15;` `        ``int` `k = 4;` `        ``Console.Write(turnOffK(n, k));` `    ``}` `}`   `// This code is contributed by Nitin Mittal.`

## PHP

 ``

## Javascript

 ``

Output:

`7`

Time Complexity: O(1)

Auxiliary Space:  O(1)

Exercise: Write a function turnOnK() that turns the k’th bit on.