Set all the bits in given range of a number

27 May, 2022
Given a non-negative number n and two values l and r. The problem is to set the bits in the range l to r in the binary representation of n, i.e, to unset bits from the rightmost lth bit to the rightmost r-th bit. 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 set.

Input : n = 50, l = 2, r = 5
Output : 62
 
Approach: Following are the steps:  
1. Find a number 'range' that has all set
   bits in given range. And all other bits
   of this number are 0.
     range = (((1 << (l - 1)) - 1) ^ 
              ((1 << (r)) - 1));

2. Now, perform "n = n | range". This will 
   set the bits in the range from l to r 
   in n.
 
C++
Java
Python3
C#
PHP
Javascript
// C++ implementation to Set bits in// the given range#include <iostream>using namespace std; // function to toggle bits in the given rangeint setallbitgivenrange(int n, int l, int r){    // calculating a number 'range' having set    // bits in the range from l to r and all other    // bits as 0 (or unset).    int range = (((1 << (l - 1)) - 1) ^                   ((1 << (r)) - 1));     return (n | range);} // Driver codeint main(){    int n = 17, l = 2, r = 3;    cout << setallbitgivenrange(n, l, r);    return 0;}
// java implementation to Set bits in// the given rangeimport java.util.*; class GFG{         // function to toggle bits in the    // given range    static int setallbitgivenrange(int n,                             int l, int r)    {                 // calculating a number 'range'        // having set bits in the range        // from l to r and all other        // bits as 0 (or unset).        int range = (((1 << (l - 1)) - 1) ^                    ((1 << (r)) - 1));             return (n | range);    }         // Driver code    public static void main(String[] args)    {        int n = 17, l = 2, r = 3;                 System.out.println(setallbitgivenrange(                                      n, l, r));    }     } // This code is contributed by Sam007.
# Python3 implementation to Set# bits in the given range # Function to toggle bits# in the given rangedef setallbitgivenrange(n, l, r):     # calculating a number 'range'    # having set bits in the range    # from l to r and all other    # bits as 0 (or unset).    range = (((1 << (l - 1)) - 1) ^                ((1 << (r)) - 1))     return (n | range) # Driver coden, l, r = 17, 2, 3print(setallbitgivenrange(n, l, r)) # This code is contributed by Anant Agarwal.
// C# implementation to Set// bits in the given rangeusing System; class GFG{    // function to toggle bits    // in the given range    static int setallbitgivenrange(int n, int l, int r)    {                 // calculating a number 'range'        // having set bits in the range        // from l to r and all other        // bits as 0 (or unset).        int range = (((1 << (l - 1)) - 1) ^                     ((1 << (r)) - 1));             return (n | range);    }         // Driver code    static void Main()    {        int n = 17, l = 2, r = 3;        Console.Write(setallbitgivenrange(n, l, r));    }     } // This code is contributed by Sam007
<?php// PHP implementation to Set// bits in the given range // function to toggle bits// in the given rangefunction setallbitgivenrange($n, $l, $r){    // calculating a number 'range'    // having set bits in the range    // from l to r and all other    // bits as 0 (or unset).    $range = (((1 << ($l - 1)) - 1) ^                  ((1 << ($r)) - 1));     return ($n | $range);} // Driver code$n = 17;$l = 2;$r = 3;echo setallbitgivenrange($n, $l, $r); // This code is contributed by Sam007?>
<script> // Javascript implementation to Set bits in// the given range // function to toggle bits in the given rangefunction setallbitgivenrange(n, l, r){    // calculating a number 'range' having set    // bits in the range from l to r and all other    // bits as 0 (or unset).    let range = (((1 << (l - 1)) - 1) ^                   ((1 << (r)) - 1));     return (n | range);} // Driver code    let n = 17, l = 2, r = 3;    document.write(setallbitgivenrange(n, l, r)); </script>
Output :  
23
Time Complexity : O(1)
Auxiliary Space : O(1)
This article is contributed by Devanshu Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
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