Day 47: Python Program to Set Bit of an Integer

def count_set_bits(n):

    count=0

    while n > 0:

        count += n & 1

        n >>= 1

        return count

num=int(input("Enter an integer"))

print(f"The number of set bits in {num}is{count_set_bits(num)}.")

#source code --> clcoding.com 

 Code Explanation:

Function: count_set_bits

def count_set_bits(n):

    count = 0

    while n > 0:

        count += n & 1

        n >>= 1

        return count

Initialization:

count = 0: Initializes a variable count to store the number of set bits.

Logic:

n & 1: This operation checks if the least significant bit (LSB) of n is 1.

& is a bitwise AND operator. It returns 1 only if both corresponding bits are 1.

For example:

5 (binary: 101) & 1 (binary: 001) = 1 (LSB is 1).

4 (binary: 100) & 1 (binary: 001) = 0 (LSB is 0).

count += n & 1: Adds 1 to count if the LSB of n is 1.

n >>= 1: Right-shifts n by 1 bit to examine the next bit.

For example:

If n = 5 (binary: 101), n >> 1 = 2 (binary: 10).

If n = 2 (binary: 10), n >> 1 = 1 (binary: 1).

Loop Condition:

The loop continues as long as n > 0, meaning there are more bits to check.

Return Value:

The function returns count, which is the total number of set bits in the binary representation of n.

num = int(input("Enter an integer"))

Prompts the user to input an integer (num).

Converts the input string to an integer using int().

print(f"The number of set bits in {num} is {count_set_bits(num)}.")

Calls the count_set_bits function with num as input.

Prints the number of set bits.

Input:

Enter an integer: 5

Execution of count_set_bits(5)

Initial value: n = 5 (binary: 101), count = 0.

First iteration:

n & 1: 101 & 001 = 1 (LSB is 1).

count += 1: count = 1.

n >>= 1: n = 2 (binary: 10).

Second iteration:

n & 1: 10 & 01 = 0 (LSB is 0).

count = 1 (no increment).

n >>= 1: n = 1 (binary: 1).

Third iteration:

n & 1: 1 & 1 = 1 (LSB is 1).

count += 1: count = 2.

n >>= 1: n = 0 (loop exits).

Return count = 2.

Output:

The number of set bits in 5 is 2.