Count trailing zero bits using lookup table

Given an integer, count the number of trailing zeroes. For example, for n = 12, its binary representation is 1100 and number of trailing zero bits is 2.

Examples:

Input : 8
Output : 3
Binary of 8 is 1000, so there are theree
trailing zero bits.

Input : 18
Output : 1
Binary of 10 is 10010, so there is one
trailing zero bit.

A simple solution is to traverse bits from LSB (Least Significant Bit) and increment count while bit is 0.





// Simple C++ code for counting trailing zeros

// in binary representation of a number

#include<bits/stdc++.h>

using namespace std;

 

int countTrailingZero(int x)

{

  int count = 0;

  while ((x & 1) == 0)

  {

      x = x >> 1;

      count++;

  }

  return count;

}

 

// Driver Code

int main()

{

    cout << countTrailingZero(11) << endl;

    return 0;

}






Output :
4