Count Set Bits in an Integer (C Program)

April 04, 2026

C Pattern Programs: Square Number and Alphabet Patterns Explained

🔷 Square Star Pattern 📋 Copy Code #include <stdio.h> int main() { int num; printf("Enter the number:\n"); scanf("%d", &num); for(int i = 1; i <= num; i++) { for(int j = 1; j <= num; j++) { printf("* ");//keep"* " } printf("\n"); } return 0; } 🔷 Reverse Square Alphabet Pattern (Column-wise) 📋 Copy Code #include <stdio.h> int main() { int num; printf("Enter the number:\n"); scanf("%d", &num); for(int i = num; i >= 1; i--) { for(int j = num; j >= 1; j--) { printf("%c ", j + 64);//%c for Character and 64 will be ASIIC VALUE } printf("\n"); } return 0; } 🔷 Reverse Square Alphabet Pattern (Row-wise) 📋 Copy Code #include <stdio.h> int main() { int num; ...

🔢 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

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C Pattern Programs: Square Number and Alphabet Patterns Explained