Set the K-th bit of a given number

Given a number n and a value k. From the right, set the kth bit in the binary representation of n. The position of LSB(or last bit) is 0, second last bit is 1 and so on. Also, 0 <= k < x, where x is the number of bits in the binary representation of n.

Examples:

Input : n = 10, k = 2
Output : 14
(10)10 = (1010)2
Now, set the 2nd bit from right.
(14)10 = (1110)2
2nd bit has been set.

Input : n = 15, k = 3
Output : 15
3rd bit of 15 is already set.

To set any bit we use bitwise OR | operator. As we already know bitwise OR | operator evaluates each bit of the result to 1 if any of the operand’s corresponding bit is set (1). In-order to set kth bit of a number we need to shift 1 k times to its left and then perform bitwise OR operation with the number and result of left shift performed just before.



                            In general, (1 << k) | n.

C++

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// C++ implementation to set the kth bit
// of the given number
#include <bits/stdc++.h>
  
using namespace std;
  
// function to set the kth bit
int setKthBit(int n, int k)
{
    // kth bit of n is being set by this operation
    return ((1 << k) | n);
}
  
// Driver program to test above
int main()
{
    int n = 10, k = 2;
    cout << "Kth bit set number = "
         << setKthBit(n, k);
    return 0;

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Java

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// Java implementation to set the kth bit
// of the given number
  
class GFG {
      
// function to set the kth bit
static int setKthBit(int n, int k)
{
    // kth bit of n is being set by this operation
    return ((1 << k) | n);
}
  
// Driver code
public static void main(String arg[])
{
    int n = 10, k = 2;
    System.out.print("Kth bit set number = "
                             setKthBit(n, k));
}
}
  
// This code is contributed by Anant Agarwal.

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Python3

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# Python implementation
# to set the kth bit
# of the given number
  
# function to set
# the kth bit
def setKthBit(n,k):
  
    # kth bit of n is being
    # set by this operation
    return ((1 << k) | n)
      
# Driver code
  
n = 10 
k = 2
  
print("Kth bit set number = ",
          setKthBit(n, k))
  
# This code is contributed
# by Anant Agarwal.

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C#

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// C# implementation to set the 
// kth bit of the given number
using System;
  
class GFG {
      
// function to set the kth bit
static int setKthBit(int n, int k)
{
    // kth bit of n is being set 
    // by this operation
    return ((1 << k) | n);
}
  
// Driver code
public static void Main()
{
    int n = 10, k = 2;
    Console.Write("Kth bit set number = " 
                    + setKthBit(n, k));
                     
}
}
  
// This code is contributed by 
// Smitha Dinesh Semwal.

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PHP

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<?php
// PHP implementation to 
// set the kth bit of 
// the given number
  
// function to set 
// the kth bit
function setKthBit($n, $k)
{
    // kth bit of n is being
    // set by this operation
    return ((1 << $k) | $n);
}
  
// Driver Code
$n = 10; $k = 2;
echo "Kth bit set number = ",
           setKthBit($n, $k);
  
// This code is contributed by m_kit
?>

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Output:

Kth bit set number = 14

This article is contributed by Ayush Jauhari. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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