__builtin_popcount long long

The __builtin_popcount function in C++ is used to count the number of set bits (1s) in an integer or a long long integer. Here is an explanation of each step involved in using this function:

1. Include the appropriate header file: In order to use the __builtin_popcount function, you need to include the header file.

2. Declare the variable: Declare a variable of type long long and assign a value to it. For example: long long num = 123456789;

3. Use the __builtin_popcount function: To count the number of set bits in the variable, use the __builtin_popcount function. Pass the variable as the argument to the function. For example: int count = __builtin_popcountll(num);

4. Retrieve the count: The __builtin_popcount function returns an integer value representing the count of set bits in the given number. You can store this value in another variable for further use or directly use it in your program. For example: cout << "Number of set bits: " << count << endl;

That's it! The __builtin_popcount function allows you to easily count the number of set bits in a long long integer without the need for any complex bitwise operations.