Python Program to Count Set Bits in an Integer

This is a Python program to count set bits in a number.

The program finds the number of ones in the binary representation of a number.

1. Create a function count_set_bits that takes a number n as argument.
2. The function works by performing bitwise AND of n with n – 1 and storing the result in n until n becomes 0.
3. Performing bitwise AND with n – 1 has the effect of clearing the rightmost set bit of n.
4. Thus the number of operations required to make n zero is the number of set bits in n.

Here is the source code of a Python program count set bits in a number. The program output is shown below.

def count_set_bits(n):
    count = 0
    while n:
        n &= n - 1
        count += 1
    return count
 
 
n = int(input('Enter n: '))
print('Number of set bits:', count_set_bits(n))

1. The user is asked to input n.
2. The number of set bits is found by calling count_set_bits on n.

Case 1:
Enter n: 9
Number of set bits: 2
 
Case 2:
Enter n: 31
Number of set bits: 5
 
Case 3:
Enter n: 1
Number of set bits: 1

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