Toggle bits in the given range

Given a non-negative number n and two values l and r. The problem is to toggle the bits in the range l to r in the binary representation of n, i.e, to toggle bits from the rightmost lth bit to the rightmost rth bit. A toggle operation flips a bit 0 to 1 and a bit 1 to 0.

Constraint: 1 <= l <= r <= number of bits in the binary representation of n.

Examples:

Input : n = 17, l = 2, r = 3
Output : 23
(17)10 = (10001)2
(23)10 = (10111)2
The bits in the range 2 to 3 in the binary
representation of 17 are toggled.

Input : n = 50, l = 2, r = 5
Output : 44

Approach: Following are the steps:

  1. Calculate num as = ((1 << r) – 1) ^ ((1 << (l-1)) – 1) or as ((1 <<r)-l). This will produce a number num having r number of bits and bits in the range l to r are the only set bits.
  2. Now, perform n = n ^ num. This will toggle the bits in the range l to r in n.

C/C++

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// C++ implementation to toggle bits in
// the given range
#include <bits/stdc++.h>
using namespace std;
  
// function to toggle bits in the given range
unsigned int toggleBitsFromLToR(unsigned int n,
                                unsigned int l, unsigned int r)
{
    // calculating a number 'num' having 'r'
    // number of bits and bits in the range l
    // to r are the only set bits
    int num = ((1 << r) - 1) ^ ((1 << (l - 1)) - 1);
  
    // toggle bits in the range l to r in 'n'
    // and return the number
//Besides this, we can calculate num as: num=(1<<r)-l .
    return (n ^ num);
}
  
// Driver program to test above
int main()
{
    unsigned int n = 50;
    unsigned int l = 2, r = 5;
    cout << toggleBitsFromLToR(n, l, r);
    return 0;
}

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Java

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// Java implementation to toggle bits in
// the given range
import java.io.*;
  
class GFG 
{
    // Function to toggle bits in the given range
    static int toggleBitsFromLToR(int n, int l, int r)
    {
        // calculating a number 'num' having 'r'
        // number of bits and bits in the range l
        // to r are the only set bits
        int num = ((1 << r) - 1) ^ ((1 << (l - 1)) - 1);
   
        // toggle bits in the range l to r in 'n'
        // and return the number
        //Besides this, we can calculate num as: num=(1<<r)-l .
        return (n ^ num);
    }
      
    // driver program
    public static void main (String[] args) 
    {
        int n = 50;
        int l = 2, r = 5;
        System.out.println(toggleBitsFromLToR(n, l, r));
    }
}
  
// Contributed by Pramod Kumar

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Python3

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# Python implementation
# to toggle bits in
# the given range
  
# function to toggle bits
# in the given range
def toggleBitsFromLToR(n,l,r):
  
    # calculating a number
    # 'num' having 'r'
    # number of bits and
    # bits in the range l
    # to r are the only set bits
    num = ((1 << r) - 1) ^ ((1 << (l - 1)) - 1)
   
    # toggle bits in the
    # range l to r in 'n'
    # Besides this, we can calculate num as: num=(1<<r)-l .
  
    # and return the number
    return (n ^ num)
  
# Driver code
  
n = 50
l = 2
r = 5
  
print(toggleBitsFromLToR(n, l, r))
  
# This code is contributed
# by Anant Agarwal.

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C#

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// C# implementation to toggle bits 
// in the given range
using System;
  
namespace Toggle
{
    public class GFG
    {     
                  
    // Function to toggle bits in the given range
    static int toggleBitsFromLToR(int n, int l, int r)
    {
        // calculating a number 'num' having 'r'
        // number of bits and bits in the range l
        // to r are the only set bits
        int num = ((1 << r) - 1) ^ ((1 << (l - 1)) - 1);
  
        // toggle bits in the range l to r in 'n'
        //Besides this, we can calculate num as: num=(1<<r)-l .
        // and return the number
        return (n ^ num);
    }
      
    // Driver Code
    public static void Main () 
    {
        int n = 50;
        int l = 2, r = 5;
        Console.Write(toggleBitsFromLToR(n, l, r));
    }
    }
}
  
// This code is contributed by Sam007.

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PHP

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<?php
// PHP implementation 
// to toggle bits in
// the given range
  
// function to toggle bits 
// in the given range
function toggleBitsFromLToR($n, $l, $r)
{
      
    // calculating a number 
    // 'num' having 'r'
    // number of bits and 
    // bits in the range l
    // to r are the only 
    // set bits
    $num = ((1 << $r) - 1) ^ 
           ((1 << ($l - 1)) - 1);
  
    // toggle bits in the 
    // range l to r in 'n'
    //Besides this, we can calculate num as: $num=(1<<$r)-$l .
    // and return the number
  
    return ($n ^ $num);
}
  
    // Driver Code
    $n = 50;
    $l = 2; $r = 5;
    echo toggleBitsFromLToR($n, $l, $r);
  
// This code is contributed by anuj_67
?>

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Output:

44

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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