C# Variable Scope and Code Blocks

using System;

namespace scope
{
    class Program
    {
        static void Main(string[] args)
        {//start of code block
         //A set of { }  makes a code block.
         //You can nest a code block inside another code block.

            //Variable a is accessible from everywhere inside this code block(but not outside of it) 
            //including any other nested code block inside this code block.
            int a = 5; 
            if (true)
            { //start of code block 1 
                //Variable b is accessible from everywhere inside code block 1(but not outside of it).
                //Including any other nested code block inside code block 1.           
                int b = 9;     
                if (true)
                { //start of code block 2  
                    //And so on ... for very further nested code block ...
                    int c = 4;
                    if (true)
                    { //start of code block 3 
                        int d = 14;

                        //As you can see a is in scope here.
                        a = d;

                    } //end of code block 3
                } //end of code block 2
            } //end of code block 1

            //But d is outside of scope here and we get an error.
            d = 15;

            Console.ReadLine();
        }//end of code block
    }

    //Another scope example with a class.
    class MyClass
    {
        //MyClassVariable is only available in this class and to other members of this class.
        int MyClassVariable = 10;

        void MyMethod() 
        {
            //Only available inside this method.
            int MyMethodVariable = 10;

            Console.WriteLine(MyMethodVariable);

            Console.WriteLine(MyClassVariable);
        }

        void MySecondMethod()
        {
            //MyMethodVariable is not available in MySecondMethod.
            Console.WriteLine(MyMethodVariable);

            Console.WriteLine(MyClassVariable);
        }

        //NOTE:
        //The members of this class can be set to be accessible/inaccessible from outside of this class.
        //This can be done by changing the access modifiers private/public/protected.
        //See my post on access modifiers for more information on the topic.
    }
}