When i was trying to read input from the user into a List ,but after reading the first number from user i'm getting an exception

Question

When i was trying to read input from the user it throws an exception of type

'System.ArgumentOutOfRangeException'

after reading the first number from user.

class Program
{
    static void Main(string[] args)
    {
        // Variable Declaration
        List<int> Marks = new List<int>();
        int i, Sum = 0, Avg;
        for (i = 0; i <= 3; i++)
        {
            Console.WriteLine("Enter Marks of Subject :");

             **I'm getting an Exception here
             It just reads one subjects marks and then throws exception

            Marks[i] = int.Parse(Console.ReadLine());

              Sum = Sum + Marks[i];**
        }


        Avg = Sum / 4;
        Console.WriteLine("Your Total is  {0} \n\nAverage is   {1}", Sum, Avg);
        Console.ReadLine();

    }
}
}

[This is the Exception i'm getting]

1

Answer 1

When you enter your for loop the list Marks is empty.
So on your first iteration, i equals 0, but you can't set Marks[i] because there is no Marks[0] . It's an empty collection.

Perhaps what you want instead of

Marks[i] = int.Parse(Console.ReadLine());  

is

Marks.Add(int.Parse(Console.ReadLine()));  

To simplify a little bit:

var mark = int.Parse(Console.ReadLine());
Marks.Add(mark);
Sum = Sum + mark;

Or instead of adding each mark to Sum one at a time you could just wait until the for loop finishes and do

Sum = Marks.Sum();