how to calculate marks in C++

#include <iostream>
#include <iomanip>

int main() {
    // Declare variables
    double marks[5];
    double totalMarks = 0;

    // Input marks from the user
    std::cout << "Enter marks for 5 subjects:" << std::endl;
    for (int i = 0; i < 5; ++i) {
        std::cout << "Subject " << i + 1 << ": ";
        std::cin >> marks[i];

        // Validate input
        while (marks[i] < 0 || marks[i] > 100) {
            std::cout << "Invalid input! Marks must be between 0 and 100. Enter again: ";
            std::cin >> marks[i];
        }

        // Accumulate total marks
        totalMarks += marks[i];
    }

    // Calculate average marks
    double averageMarks = totalMarks / 5;

    // Display results
    std::cout << std::fixed << std::setprecision(2);
    std::cout << "Total Marks: " << totalMarks << std::endl;
    std::cout << "Average Marks: " << averageMarks << std::endl;

    return 0;
}