🔢 Count Set Bits in an Integer (C Program)

#include<stdio.h>
int count_set_bits(int num)
{
    unsigned int mask = (unsigned int)num;
    int count = 0;
    while(mask)
    {
        count += mask & 1;
        mask >>= 1;
    }
    return count; 
}
int main( )
{
    int number;
  //  printf("Enter the number: ");
    scanf("%d", &number);
    int result = count_set_bits(number);
    printf("The count of set bits is %d\\n", result);
}
  

📘 Explanation:

This program counts the number of set bits (1s) in the binary representation of an integer using bitwise operations.

🔹 `mask & 1` checks the least significant bit (LSB) of the number.
🔹 If it's 1, `count` is incremented.
🔹 The mask is then right-shifted using `mask >>= 1` to check the next bit.
🔹 The loop continues until the entire binary number is processed.

🔸 Note: Casting `num` to `unsigned int` ensures correct behavior for negative numbers (avoiding sign extension).

🔍 Sample Output:

Input:
13

Output:
The count of set bits is 3
    

🏷️ Keywords:

count set bits C, number of 1s in binary, bitwise AND, C bit manipulation, right shift, count bits using loop