[DotNetDevelopment] Why this

[VIKAS GARG]

using System;
using System.IO;

class ShowFile
{
    public static void Main(string[] args)
    {
        int i;
        FileStream fin;

        try
        {
            fin = new FileStream(args[0], FileMode.Open);
        }
        catch (FileNotFoundException exc)
        {
            Console.WriteLine(exc.Message);
            return;
        }
        catch (IndexOutOfRangeException exc)
        {
            Console.WriteLine(exc.Message + "\nUsage: ShowFile File");
            return;
        }

        // read bytes until EOF is encountered
        do
        {
            try
            {
                i = fin.ReadByte();
            }
            catch (Exception exc)
            {
                Console.WriteLine(exc.Message);
                return;
            }
            if (i != -1) Console.Write((char)i);
        } while (i != -1);

        fin.Close();
    }
}




In such kind of progg where we are required to give the name of the file at
the runtime and if we don't provide the name of the file, why it gives error
"Index was outside the bounds of array"