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.
mask = 1 << position

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
(n & ~mask) | ((b << p) & mask)

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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