Count Set Bits in an Integer (C Program)

August 16, 2026

Merge Sort in C++

Merge Sort in C++ Introduction Merge Sort is a popular sorting algorithm that follows the Divide and Conquer approach. It divides an array into smaller subarrays, recursively sorts those subarrays, and finally merges the sorted subarrays to produce a completely sorted array. In this tutorial, we will learn how to implement Merge Sort in C++ . The program divides the array into two halves using the mid index, recursively sorts both halves, and then combines them using the merge() function. Merge Sort has a time complexity of O(n log n) in the best, average, and worst cases. Table of Contents Algorithm C++ Program Input Sample Output Output Explanation Dry Run Flow of Execution Time Complexity Space Complexity Applications Key Points Interview Questions Frequently Asked Questions Keywords Conclusion Algorithm Start the program. Read the size of the array. Read the array elements from the user. Call the mer...

🔢 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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Merge Sort in C++