Two Dimensional Array - C# Programming Exercise

using System;  // Import the System namespace for basic functionality

class Program  // Define the main class
{
    static void Main()  // The entry point of the program
    {
        // Create a two-dimensional array to store marks for 2 groups of 10 pupils
        double[,] marks = new double[2, 10];  
        double group1Sum = 0, group2Sum = 0;  // Variables to store the sum of marks for each group
        double group1Average, group2Average;  // Variables to store the average marks for each group
        
        // Ask the user to enter marks for the pupils
        Console.WriteLine("Enter marks for 20 pupils (2 groups of 10):");
        
        // Input marks for Group 1 (10 pupils)
        for (int i = 0; i < 10; i++)
        {
            Console.Write($"Enter mark for pupil {i + 1} in Group 1: ");
            while (!double.TryParse(Console.ReadLine(), out marks[0, i]) || marks[0, i] < 0)
            {
                Console.WriteLine("Invalid input. Please enter a valid mark (non-negative number).");
                Console.Write($"Enter mark for pupil {i + 1} in Group 1: ");
            }
            group1Sum += marks[0, i];  // Add the mark to the sum for Group 1
        }

        // Input marks for Group 2 (10 pupils)
        for (int i = 0; i < 10; i++)
        {
            Console.Write($"Enter mark for pupil {i + 1} in Group 2: ");
            while (!double.TryParse(Console.ReadLine(), out marks[1, i]) || marks[1, i] < 0)
            {
                Console.WriteLine("Invalid input. Please enter a valid mark (non-negative number).");
                Console.Write($"Enter mark for pupil {i + 1} in Group 2: ");
            }
            group2Sum += marks[1, i];  // Add the mark to the sum for Group 2
        }

        // Calculate the average marks for each group
        group1Average = group1Sum / 10;
        group2Average = group2Sum / 10;

        // Display the averages for each group
        Console.WriteLine($"\nAverage mark for Group 1: {group1Average:F2}");
        Console.WriteLine($"Average mark for Group 2: {group2Average:F2}");
    }
}