using System;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main()
        {
            byte[] b2 = new byte[6];

            FileStream f1;
            FileStream f2;

            f1 = new FileStream("abc.txt", FileMode.Open, FileAccess.Read);
            f2 = new FileStream("xyz.txt", FileMode.Open, FileAccess.Write);

            if (f1.CanRead)
                Console.WriteLine("Yes, It can read.");
            else
                Console.WriteLine("Yes, It can not read.");


            f1.Close();

            if (f2.CanRead)
                Console.WriteLine("Yes, It can read.");
            else
                Console.WriteLine("Yes, It can not read.");

            f2.Close();
        }
    }
}

Output

Yes, It can read.
Yes, It can not read.

In above program, we need to remember, when we use "FileStream" class then we need to include System.IO namespace in the program.