Example: Sum of Series 1 1 2 1 3 ... in C++

// Sum of Series 1 1 2 1 3 ...
#include <iostream>
using namespace std;

int main() {
    // Step 1: Declare variables for the number of terms and the sum
    int n;
    long long sum = 0; // Use long long for sum to prevent potential overflow for large 'n'

    // Step 2: Prompt user for the number of terms
    cout << "Enter the number of terms (n) for the series: ";
    cin >> n;

    // Step 3: Input validation (optional, but good practice)
    if (n <= 0) {
        cout << "Please enter a positive integer for n." << endl;
        return 1; // Indicate an error
    }

    // Step 4: Loop through each term from 1 to n
    for (int i = 1; i <= n; ++i) {
        // Step 5: Check if the current position 'i' is odd or even
        if (i % 2 != 0) { // If 'i' is odd
            sum += (i + 1) / 2;
        } else { // If 'i' is even
            sum += 1;
        }
    }

    // Step 6: Display the calculated sum
    cout << "The sum of the series up to " << n << " terms is: " << sum << endl;

    return 0;
}