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.
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
value & ~mask
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 <bits/stdc++.h> 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
<?php // PHP program to modify a bit // at position p in n to b. // Returns modified n. function modifyBit($n, $p, $b) { $mask = 1 << $p; return ($n & ~$mask) | (($b << $p) & $mask); } // Driver code echo modifyBit(6, 2, 0),"\n"; echo modifyBit(6, 5, 1) ,"\n"; // This code is contributed by ajit ?> |
Output :
2 38
Time Complexity :O(1)
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