# Modify a bit at a given position

Given a number n, a position p and a binary value b, we need to change the bit at position p in n to value b.

Examples :

```Input : n = 7, p = 2, b = 0
Output : 3
7 is 00000111 after clearing bit at
2rd position, it becomes 0000011.

Input : n = 7, p = 3, b = 1
Output : 15
7 is 00000111 after setting bit at
3rd position it becomes 00001111.
```

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

```We first create a mask that has set bit only
at given position using bit wise shift.

Then to change value of bit to b, we first
make it 0 using below operation

After changing it 0, we change it to b by
doing or of above expression with following
(b << p) & mask, i.e., we return
```

Below is the implementation of above steps :

## C++

 `// CPP program to modify a bit at position ` `// p in n to b. ` `#include ` `using` `namespace` `std; ` ` `  `// Returns modified n. ` `int` `modifyBit(``int` `n, ``int` `p, ``int` `b) ` `{ ` `    ``int` `mask = 1 << p; ` `    ``return` `(n & ~mask) | ((b << p) & mask); ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``cout << modifyBit(6, 2, 0) << endl; ` `    ``cout << modifyBit(6, 5, 1) << endl; ` `    ``return` `0; ` `} `

## Java

 `// Java program to modify a bit ` `// at position p in n to b. ` `import` `java.io.*; ` ` `  `class` `GFG  ` `{ ` `     `  `// Returns modified n. ` `public` `static` `int` `modifyBit(``int` `n,  ` `                            ``int` `p,  ` `                            ``int` `b) ` `{ ` `    ``int` `mask = ``1` `<< p; ` `    ``return` `(n & ~mask) |  ` `           ``((b << p) & mask); ` `} ` `    ``// Driver Code ` `    ``public` `static` `void` `main (String[] args) ` `    ``{ ` `        ``System.out.println(modifyBit(``6``, ``2``, ``0``)); ` `        ``System.out.println (modifyBit(``6``, ``5``, ``1``)); ` `    ``} ` `} ` ` `  `// This code is contributed by m_kit `

## Python3

 `# Python3 program to modify a bit at position ` `# p in n to b. ` ` `  `# Returns modified n. ` `def` `modifyBit( n,  p,  b): ` `    ``mask ``=` `1` `<< p ` `    ``return` `(n & ~mask) | ((b << p) & mask) ` `  `  `# Driver code ` `def` `main(): ` `    ``print``(modifyBit(``6``, ``2``, ``0``)) ` `    ``print``(modifyBit(``6``, ``5``, ``1``)) ` `     `  `if` `__name__ ``=``=` `'__main__'``: ` `    ``main() ` `# This code is contributed by PrinciRaj1992 `

## C#

 `// C# program to modify a bit ` `// at position p in n to b. ` `using` `System; ` ` `  `class` `GFG ` `{ ` `// Returns modified n. ` `public` `static` `int` `modifyBit(``int` `n,  ` `                            ``int` `p,  ` `                            ``int` `b) ` `{ ` `    ``int` `mask = 1 << p; ` `    ``return` `(n & ~mask) |  ` `           ``((b << p) & mask); ` `} ` ` `  `    ``// Driver Code ` `    ``static` `public` `void` `Main () ` `    ``{ ` `     `  `        ``Console.WriteLine(modifyBit(6, 2, 0)); ` `        ``Console.WriteLine(modifyBit(6, 5, 1)); ` `    ``} ` `} ` ` `  `// This code is contributed by ajit `

## PHP

 ` `

Output :

``` 2
38
```

Time Complexity :O(1)

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