Swap all odd and even bits Last Updated : 23 Jul, 2025 Comments Improve Suggest changes Like Article Like Report Try it on GfG Practice Given an unsigned integer N. The task is to swap all odd bits with adjacent even bits. Examples: Input: 23Output: 43Explanation: 23 (00010111) should be converted to 43 (00101011). Input: 2Output: 1 Recommended PracticeSwap all odd and even bitsTry It! Naive Approach: Below is the idea to solve the problem For every even index i in the binary representation of N starting from index 0 swap bits with (i+1)th index. Follow the steps below to implement the idea: Find the bit at i and i+1 index.To swap the bits subtract and add corresponding values.To remove bit at ith bit to i+1. subtract i_bit<<i and add it at i+1 index for that we need to add i_bit<<(i+1).Similarly subtract (i+1)th bit and add it to ith index. Below is the implementation of above approach. C++ // C++ program to swap even and // odd bits of a given number #include <bits/stdc++.h> using namespace std; // Function to swap even // and odd bits unsigned int swapBits(unsigned int x) { for (int i = 0; i < 32; i += 2) { // Find i th bit int i_bit = (x >> i) & 1; // Find i+1 th bit int i_1_bit = (x >> (i + 1)) & 1; // Remove i_bit x = x - (i_bit << i) // Remove i+1 th bit - (i_1_bit << (i + 1)) // Put i_bit at i+1 location + (i_bit << (i + 1)) // Put i+1 bit at i location + (i_1_bit << i); } return x; } // Driver code int main() { // 00010111 unsigned int x = 23; // Function Call cout << swapBits(x); return 0; } // This code is contributed by Amandeep Gupta Java // Java program to swap even and // odd bits of a given number import java.io.*; class GFG { // Function to swap even // and odd bits static int swapBits(int x) { for (int i = 0; i < 32; i += 2) { int i_bit = (x >> i) & 1; // find i th bit int i_1_bit = (x >> (i + 1)) & 1; // find i+1 th bit x = x - (i_bit << i) // remove i_bit - (i_1_bit << (i + 1)) // remove i+1 th bit + (i_bit << (i + 1)) // put i_bit at i+1 location + (i_1_bit << i); // put i+1 bit at i location } return x; } // Driver code public static void main(String[] args) { int x = 23; // 00010111 // Output is 43 (00101011) System.out.print(swapBits(x)); } } // This code is contributed by subham348. Python3 # Python program to swap even and # odd bits of a given number # Function to swap even # and odd bits def swapBits(x): # Get all even bits of x even_bits = x & 0xAAAAAAAA # Get all odd bits of x odd_bits = x & 0x55555555 # Right shift even bits even_bits >>= 1 # Left shift odd bits odd_bits <<= 1 for i in range(0,32,2): i_bit = (x >> 1) & 1; # find i th bit i_1_bit = (x >> (i + 1)) & 1; # find i+1 th bit x = x - (i_bit << i) # remove i_bit - (i_1_bit << (i + 2)) # remove i+1 th bit + (i_bit << (i + 1)) # put i_bit at i+1 location + (i_1_bit << i); # put i+1 bit at i location # Combine even and odd bits return (even_bits | odd_bits) # Driver code if __name__ == '__main__': x = 23; # 00010111 # Output is 43 (00101011) print(swapBits(x)); # This code is contributed by Rajput-Ji C# // C# program to swap even and // odd bits of a given number using System; class GFG { // Function to swap even // and odd bits static int swapBits(int x) { for (int i = 0; i < 32; i += 2) { int i_bit = (x >> i) & 1; // find i th bit int i_1_bit = (x >> (i + 1)) & 1; // find i+1 th bit x = x - (i_bit << i) // remove i_bit - (i_1_bit << (i + 1)) // remove i+1 th bit + (i_bit << (i + 1)) // put i_bit at i+1 location + (i_1_bit << i); // put i+1 bit at i location } return x; } // Driver code public static void Main() { int x = 23; // 00010111 // Output is 43 (00101011) Console.Write(swapBits(x)); } } // This code is contributed by subham348. JavaScript <script> // JavaScript Program to implement // the above approach // Function to swap even // and odd bits function swapBits( x) { for(let i = 0; i < 32; i += 2){ let i_bit = ( x >> i ) & 1; // find i th bit let i_1_bit = (x >> ( i+1 )) & 1; // find i+1 th bit x = x - ( i_bit << i) // remove i_bit - ( i_1_bit << ( i+1 ) ) // remove i+1 th bit + ( i_bit << ( i+1 ) ) // put i_bit at i+1 location + ( i_1_bit << i ); // put i+1 bit at i location } return x; } // Driver code let x =23; // 00010111 // Output is 43 (00101011) document.write(swapBits(x)); // This code is contributed by Potta Lokesh </script> Output43 Time Complexity: O(1)Auxiliary Space: O(1) Efficient Approach: Below is the idea to solve the problem. The value even_bits obtained by even bits of N and Right shifted (>>) by 1 on even_bits and similarly obtain value odd_bits of odd bits of N and perform left shift (<<) by 1 operation on odd_bits. Now (odd_bits | even_bits) will give the desired value. Follow the below steps to implement the approach: Initialize variable even_bits with bitwise and of N with 0xAAAAAAAA(32 bit number with all even bits set as 1 and all odd bits as 0). Initialize variable odd_bits with bitwise and of N with 0x55555555. The number 0x55555555 is a 32 bit number with all odd bits set as 1 and all even bits as 0. Right shift even_bits by 1 and Left shift odd_bits by 1. Return or of even_bits with odd_bits . Below is the Implementation of above approach. C++ // C++ program to swap even and // odd bits of a given number #include <bits/stdc++.h> using namespace std; // Function to swap even // and odd bits unsigned int swapBits(unsigned int N) { // Get all even bits of x unsigned int even_bits = N & 0xAAAAAAAA; // Get all odd bits of x unsigned int odd_bits = N & 0x55555555; // Right shift even bits even_bits >>= 1; // Left shift odd bits odd_bits <<= 1; // Combine even and odd bits return (even_bits | odd_bits); } // Driver code int main() { // 00010111 unsigned int N = 23; //Function Call cout<<swapBits(N); return 0; } // This code is contributed by rathbhupendra C // C program to swap even and // odd bits of a given number #include <stdio.h> // Function to swap even // and odd bits unsigned int swapBits(unsigned int x) { // Get all even bits of x unsigned int even_bits = x & 0xAAAAAAAA; // Get all odd bits of x unsigned int odd_bits = x & 0x55555555; even_bits >>= 1; // Right shift even bits odd_bits <<= 1; // Left shift odd bits return (even_bits | odd_bits); // Combine even and odd bits } // Driver program to test above function int main() { unsigned int x = 23; // 00010111 // Output is 43 (00101011) printf("%u ", swapBits(x)); return 0; } Java // Java program to swap even // and odd bits of a given number class GFG{ // Function to swap even // and odd bits static int swapBits(int x) { // Get all even bits of x int even_bits = x & 0xAAAAAAAA; // Get all odd bits of x int odd_bits = x & 0x55555555; // Right shift even bits even_bits >>= 1; // Left shift even bits odd_bits <<= 1; // Combine even and odd bits return (even_bits | odd_bits); } // Driver program to test above function public static void main(String[] args) { int x = 23; // 00010111 // Output is 43 (00101011) System.out.println(swapBits(x)); } } // This code is contributed by Smitha Dinesh Semwal Python 3 # Python 3 program to swap even # and odd bits of a given number # Function for swapping even # and odd bits def swapBits(x) : # Get all even bits of x even_bits = x & 0xAAAAAAAA # Get all odd bits of x odd_bits = x & 0x55555555 # Right shift even bits even_bits >>= 1 # Left shift odd bits odd_bits <<= 1 # Combine even and odd bits return (even_bits | odd_bits) # Driver program # 00010111 x = 23 # Output is 43 (00101011) print(swapBits(x)) # This code is contributed # by Nikita Tiwari. C# // C# program to swap even and odd bits // of a given number using System; class GFG { // Function to swap even // and odd bits static long swapBits(int x) { // Get all even bits of x long even_bits = x & 0xAAAAAAAA; // Get all odd bits of x long odd_bits = x & 0x55555555; // Right shift even bits even_bits >>= 1; // Left shift even bits odd_bits <<= 1; // Combine even and odd bits return (even_bits | odd_bits); } // Driver program to test above function public static void Main() { int x = 23; // 00010111 // Output is 43 (00101011) Console.Write(swapBits(x)); } } // This code is contributed by Sam007. PHP <?php // PHP program to swap even and // odd bits of a given number // Function to swap even // and odd bits function swapBits( $x) { // Get all even bits of x $even_bits = $x & 0xAAAAAAAA; // Get all odd bits of x $odd_bits = $x & 0x55555555; // Right shift even bits $even_bits >>= 1; // Left shift odd bits $odd_bits <<= 1; // Combine even and odd bits return ($even_bits | $odd_bits); } // Driver Code // 00010111 $x = 23; // Output is 43 (00101011) echo swapBits($x); // This code is contributed by Ajit ?> JavaScript <script> // java script program to swap even and // odd bits of a given number // Function to swap even // and odd bits function swapBits( x) { // Get all even bits of x even_bits = x & 0xAAAAAAAA; // Get all odd bits of x odd_bits = x & 0x55555555; // Right shift even bits even_bits >>= 1; // Left shift odd bits odd_bits <<= 1; // Combine even and odd bits return (even_bits | odd_bits); } // Driver Code // 00010111 let x = 23; // Output is 43 (00101011) document.write(swapBits(x)); // This code is contributed by sravan kumar </script> Output43 Time Complexity: O(1)Auxiliary Space: O(1) Swap all odd and even bits | DSA Problem Comment More infoAdvertise with us Next Article Types of Asymptotic Notations in Complexity Analysis of Algorithms K kartik Follow Improve Article Tags : Bit Magic DSA Practice Tags : Bit Magic Similar Reads Basics & PrerequisitesTime Complexity and Space ComplexityMany times there are more than one ways to solve a problem with different algorithms and we need a way to compare multiple ways. 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