Example: Sum of First n Odd Numbers (For Loop) in C++

// Sum of First n Odd Numbers (For Loop)
#include <iostream>
using namespace std;

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

    // Step 2: Prompt user for input
    cout << "Enter the number of odd terms to sum: ";
    cin >> n_terms;

    // Step 3: Input validation
    if (n_terms <= 0) {
        cout << "Number of terms must be positive." << endl;
        return 1; // Indicate an error
    }

    // Step 4: Iterate and sum the odd numbers
    cout << "Series: ";
    for (int i = 1; i <= n_terms; ++i) {
        int current_odd = 2 * i - 1; // Formula to get the i-th odd number
        sum += current_odd;
        cout << current_odd;
        if (i < n_terms) {
            cout << " + ";
        }
    }
    cout << endl;

    // Step 5: Display the result
    cout << "Sum of the first " << n_terms << " odd numbers is: " << sum << endl;

    return 0;
}