Process is terminated stack overflow exception

Beginning with C# 3.0, you now have auto-implemented Properties where what used to be the standard use of a "backing-field" variable is no longer necessary. If you write this code:

public int a { get; set; }

The compiler will generate a hidden private variable for you.

Here's what your code might look like taking advantage of this:

using System;

namespace ConsoleAccessPrivateMembers
{
    internal class MyPrivateClassMem
    {
        // parameterless ctor
        public MyPrivateClassMem()
        {
            a = 10;
            b = 20;
        }

        // ctor with supplied parameters
        public MyPrivateClassMem(int parametera, int parameterb)
        {
            a = parametera;
            b = parameterb;
        }

        // auto-implemented public properties
        public int a { get; set; }
        public int b { get; set; }

        public int add()
        {
            return a + b;
        }
    }

    internal class MyInput
    {
        private static void Main(string[] args)
        {
            var obj1 = new MyPrivateClassMem();
            obj1.a = 1;
            obj1.b = 2;
            Console.WriteLine("obj1 add result: " + obj1.add());

            var obj2 = new MyPrivateClassMem(100, 200);
            Console.WriteLine("obj2 add result: " + obj2.add());

            // keep the Console window open
            Console.ReadLine();
        }
    }
}

Note the use of a parameterless Constructor that allows for the initialization of 'a and 'b to default values.

Also note a second, optional, Constructor with parameters supplied, so you can initialize 'a and 'b, if you wish, when you create an instance of the Class 'MyPrivateClassMem.