bitwise count total set bits

To count the total number of set bits using bitwise operations in C++, you can follow these steps:

  1. Initialize a variable, let's call it "count," to 0. This variable will keep track of the total number of set bits.

  2. Use a loop to iterate through each bit of the given number. You can use a for loop to iterate from 0 to the number of bits in the data type (usually 32 or 64 bits).

  3. Inside the loop, perform a bitwise AND operation between the given number and a bit mask. The bit mask is created by shifting the value 1 to the left by the current bit position. For example, if the current bit position is 0, the bitmask will be 0b00000001. If the current bit position is 1, the bitmask will be 0b00000010, and so on.

  4. Check if the result of the bitwise AND operation is non-zero. If it is, increment the count variable by 1. This means that the current bit is set to 1.

  5. Continue the loop until all the bits have been checked.

  6. After the loop ends, the count variable will hold the total number of set bits in the given number.

Here is an example implementation in C++:

#include <iostream>

int countSetBits(int num) {
    int count = 0;
    int numBits = sizeof(num) * 8; // Assuming an integer is 32 bits

    for (int i = 0; i < numBits; i++) {
        int bitmask = 1 << i;
        if (num & bitmask) {
            count++;
        }
    }

    return count;
}

int main() {
    int num = 10; // Example number
    int setBits = countSetBits(num);
    std::cout << "Total set bits in " << num << ": " << setBits << std::endl;

    return 0;
}

In this example, the function countSetBits() takes an integer num as input and returns the total number of set bits in that number. The main() function demonstrates how to use this function by passing a sample number 10 and printing the result.