reverse_bits.cpp

//Given an integer, reverse its bits using binary operators.
#include <iostream>
#include <bitset>
using namespace std;

// A macro that defines the size of an integer
#define INT_SIZE sizeof(int) * 8

// Function to reverse bits of a given integer
int reverseBits(int n)
{
    int pos = INT_SIZE - 1; // maintains shift

    // store reversed bits of `n`. Initially, all bits are set to 0
    int reverse = 0;

    // do till all bits are processed
    while (pos >= 0 && n)
    {
        // if the current bit is 1, then set the corresponding bit in the result
        if (n & 1)
        {
            reverse = reverse | (1 << pos);
        }

        n >>= 1; // drop current bit (divide by 2)
        pos--;   // decrement shift by 1
    }

    return reverse;
}

int main()
{
    int n = 54;

    cout << n << " in binary is " << bitset<32>(n) << endl;
    cout << "On reversing bits " << bitset<32>(reverseBits(n));

    return 0;
}