Open-Source Internship opportunity by OpenGenus for programmers. Apply now.

In this article, we have designed and implemented a C Program to count trailing zeros using bitwise operators only. This will involve AND and Left Shift bitwise operation.

**Table of contents**:

- Problem Statement
- Approach 1
- C Program to count trailing zeros using bitwise operator

Learn:

## Problem Statement

The problem is to count the number of trailing zeroes in a binary format representation of a given Integer. The challenge is to use only bitwise operations.

If the integer is 160, then binary representation will be `0b10100000`

. The number of trailing zeroes will be 5.

160 = 0b10100000

In this problem, we need not convert the number to binary format.

Implement the approach in C Programming Language.

## Approach 1

The key idea to count trailing zeros using bitwise operations are:

- Check the lowest significant bit and if it is 0, increase count by 1.
- Check next bit from left to right (increasing significance).
- If you encounter a bit to be 1, end the process and return the count.

To check the lowest significant bit, you can do AND with 1.

```
N & 1
```

Similarly:

- 1: Lowest significant bit is set to 1 only
- 1 << 1: 2nd lowest significant bit is set to 1 only
- 1 << 2: 3rd lowest significant bit is set to 1 only
- and so on.

Only, AND and Left Shift bitwise operations are used in this approach.

## C Program to count trailing zeros using bitwise operator

Following is the complete C Program to count trailing zeros using bitwise operator:

```
// Part of iq.opengenus.org
#include<stdio.h>
int countTrailingZeros(int num)
{
int mask = 1;
int count = 0;
while (mask != 0) {
if ((num & mask) == 0) {
++ count;
}
else {
break;
}
mask = mask << 1;
}
return count;
}
int main() {
int integer_number = 160;
printf("Number of trailing zeros in %d in binary format is: %d",
integer_number, countTrailingZeros(integer_number));
return 0;
}
```

Output:

```
Number of trailing zeros in 160 in binary format is: 5
```

With this article at OpenGenus, you must have the complete idea of how to implement a C Program to count trailing zeros using bitwise operator.