# Set the rightmost unset bit

Given a non-negative number n. The problem is to set the rightmost unset bit in the binary representation of n

Examples:

```Input : 21
Output : 23
(21)10 = (10101)2
Rightmost unset bit is at position 2(from right) as
highlighted in the binary representation of 21.
(23)10 = (10111)2
The bit at position 2 has been set.

Input : 2
Output : 3
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

This post discusses another method.

Let the input number be n. n+1 would have all the bits flipped after the rightmost unset bit (including the unset bit). So, doing n|(n+1) would give us the required result.

## C++

 `#include ` ` `  `// sets the rightmost unset bit ` `// of n and returns the result ` `int` `fun(unsigned ``int` `n) ` `{ ` `    ``return` `n | (n + 1); ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``int` `n = 5; ` `    ``printf``(``"The number after setting the"``); ` `    ``printf``(``" rightmost unset bit %d"``, fun(n)); ` `    ``return` `0; ` `} `

## Java

 `class` `GFG { ` `     `  `    ``// sets the rightmost unset bit ` `    ``// of n and returns the result ` `    ``static` `int` `fun(``int` `n) ` `    ``{ ` `        ``return` `n | (n + ``1``); ` `    ``} ` `     `  `    ``// Driver Code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``int` `n = ``5``; ` `        ``System.out.printf(``"The number "` `                  ``+ ``"after setting the"``); ` `        ``System.out.printf(``" rightmost "` `              ``+ ``" unset bit %d"``, fun(n)); ` `    ``} ` `} ` ` `  `// This code is contributed by Smitha `

## Python3

 `# sets the rightmost unset bit ` `# of n and returns the result ` `def` `fun(n): ` ` `  `    ``return` `n | (n ``+` `1``) ` ` `  `# Driver Code ` `n ``=` `5` `print``(``"The number after setting the"``, end``=``"") ` `print``(``" rightmost unset bit "``, fun(n)) ` ` `  `# This code is contributed by Smitha `

## C#

 `using` `System; ` ` `  `class` `GFG { ` `     `  `    ``// sets the rightmost unset bit ` `    ``// of n and returns the result ` `    ``static` `int` `fun(``int` `n) ` `    ``{ ` `        ``return` `n | (n + 1); ` `    ``} ` `     `  `    ``// Driver Code ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``int` `n = 5; ` `        ``Console.Write(``"The number "` `            ``+ ``"after setting the"``); ` `        ``Console.Write(``" rightmost "` `           ``+ ``"unset bit "``+ fun(n)); ` `    ``} ` `} ` ` `  `// This code is contributed by Smitha `

## PHP

 ` `

Output :

`The number after setting the rightmost unset bit 7`

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