Change all even bits in a number to 0
Given a number, change all bits at even positions to 0.
Examples:
Input : 30 Output : 10 Binary representation of 11110. Bits at Even positions are highlighted. After making all of them 0, we get 01010 Input : 10 Output : 10
Method 1 (Bit Traversal)
The idea is to traverse through all even bits. We accumulate all powers of 2 in a number to subtract. Finally we subtract the accumulated value from n to obtain the result.
C++
// C++ program to change even // bits to 0. #include<bits/stdc++.h> using namespace std; // Returns modified number with // all even bits 0. int changeEvenBits(int n) { // To store sum of bits // at even positions. int to_subtract = 0; // To store bits to shift int m = 0; // One by one put all even // bits to end for (int x = n; x; x >>= 2) { // If current last bit // is set, add it to ans if (x & 1) to_subtract += (1 << m); // Next shift position m += 2; } return n - to_subtract; } // Driver code int main() { int n = 30; cout << changeEvenBits(n) << endl; return 0; } |
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Java
// Java program to change even // bits to 0. import java.util.*; class GFG { // Returns modified number with // all even bits 0. static int changeEvenBits(int n) { // To store sum of bits // at even positions. int to_subtract = 0; // To store bits to shift int m = 0; // One by one put all even // bits to end for (int x = n; x>0; x >>= 2) { // If current last bit // is set, add it to ans if ((x & 1) > 0) to_subtract += (1 << m); // Next shift position m += 2; } return n - to_subtract; } // Driver code public static void main(String[] args) { int n = 30; System.out.println(changeEvenBits(n)); } } /* This code is contributed by Mr. Somesh Awasthi */ |
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Python
# Python program to change even # bits to 0. # Returns modified number with # all even bits 0. def changeEvenBits(n): # To store sum of bits # at even positions. to_subtract = 0 # To store bits to shift m = 0 # One by one put all even # bits to end x = n while(x): # If current last bit # is set, add it to ans if (x & 1): to_subtract += (1 << m) # Next shift position m += 2 x >>= 2 return n - to_subtract # Driver code n = 30print changeEvenBits(n) # This code is contributed by Sachin Bisht |
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C#
// C# program to change even // bits to 0. using System; class GFG { // Returns modified number with // all even bits 0. static int changeEvenBits(int n) { // To store sum of bits // at even positions. int to_subtract = 0; // To store bits to shift int m = 0; // One by one put all even // bits to end for (int x = n; x > 0; x >>= 2) { // If current last bit // is set, add it to ans if ((x & 1) > 0) to_subtract += (1 << m); // Next shift position m += 2; } return n - to_subtract; } // Driver code public static void Main() { int n = 30; Console.Write(changeEvenBits(n)); } } // This code is contributed by nitin mittal. |
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PHP
<?php // PHP program to change even // bits to 0. // Returns modified number with // all even bits 0. function changeEvenBits($n) { // To store sum of bits // at even positions. $to_subtract = 0; // To store bits to shift $m = 0; // One by one put all even // bits to end for ($x = $n; $x; $x >>= 2) { // If current last bit // is set, add it to ans if ($x & 1) $to_subtract += (1 << $m); // Next shift position $m += 2; } return $n - $to_subtract; } // Driver code $n = 30; echo changeEvenBits($n) ; // This code is contributed by nitin mittal ?> |
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Output :
10
Method 2 (Bitmask)
C++
#include<bits/stdc++.h> using namespace std; int convertEvenBitToOne(int n) { return (n & 0xaaaaaaaa); } int main() { int n = 30; cout << convertEvenBitToOne(n); return 0; } |
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Java
// Java program using Bitmask to // Change all even bits in a // number to 0 import java.io.*; class GFG { static int convertEvenBitToOne(int n) { return (n & 0xaaaaaaaa); } // Driver code public static void main (String[] args) { int n = 30; System.out.println( convertEvenBitToOne(n)); } } // This code is contributed by anuj_67. |
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Python
def convertEvenBitToOne(n): return (n & 0xaaaaaaaa) # Driver code n = 30print convertEvenBitToOne(n) # This code is contributed by Sachin Bisht |
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C#
// C# program using Bitmask to // Change all even bits in a // number to 0 using System; class GFG { static long convertEvenBitToOne(int n) { return (n & 0xaaaaaaaa); } // Driver code public static void Main () { int n = 30; Console.WriteLine( convertEvenBitToOne(n)); } } // This code is contributed by anuj_67. |
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PHP
<?php // PHP program using Bitmask to // Change all even bits in a // number to 0 function convertEvenBitToOne($n) { return ($n & 0xaaaaaaaa); } // Driver Code $n = 30; echo convertEvenBitToOne($n); // This code is contributed by anuj_67. ?> |
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Output :
10
This article is contributed by RISHABH RAJ JHA . 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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