for while and or switch case array text

//using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TextHello
{
    class Program
    {
        // Hellow world program
        static void Main(string[] args)
        {
            System.Console.WriteLine("Hello World");
            int x = 10;
            int y = 3;
            int result = x % y;
            System.Console.WriteLine("result =" + result);
            System.Console.WriteLine("{0} + {1} = {2}", x, y, (x + y));
            System.Console.ReadLine();
            // for loop
            for (int i = 10; i >= 0; i--)
            {
                System.Console.WriteLine("i=" + i);
            }
            // while loop
            int ix = 10;
            while (ix >= 0)
            {
                System.Console.WriteLine("ix =" + ix);
                ix--; // ix = ix-1;
            }
            // do while loop
            // executes at least one line
            int iy = 10;
            do
            {
                System.Console.WriteLine("iy =" + iy);
                iy--;
            } while (iy > 0);
            // and or statemnet
            // short and &&  or || vs. regular and &  or |
            // shorts ones don't check the second arg once the first arg is satisfied.
            // regular ones always checks every arg in bracket
            System.Console.WriteLine("-------------- and or statement && ||");
            x = -10;
            y = 10;
            if (x >= 0 && y >= 0)
            {
                System.Console.WriteLine("both numbers positive");
            }
            else if (x >= 0 || y >= 0)
            {
                System.Console.WriteLine("at least one number positive");
            }
            else
            {
                System.Console.WriteLine("both numbers negative");
            }
            // switch case
            System.Console.WriteLine("----------- switch case");
            string j = "Two";
            switch (j)
            {

                case "Zero":
                    System.Console.WriteLine("value is 0");
                    break;
                case "One":
                    System.Console.WriteLine("value is 1");
                    break;
                case "Two":
                    System.Console.WriteLine("value is 2");
                    break;
                case "Three":
                    System.Console.WriteLine("value is 3");
                    break;
                default:
                    System.Console.WriteLine("value not found");
                    break;

            }
            //
            // declare array
            //
            System.Console.WriteLine("--------------- array manipulation");
            int[] a = { 10, 20, 30, 40, 50, 60};
            System.Console.WriteLine(a[3]);
            a[4] = 55;
            System.Console.WriteLine(a[4]);
            for (int i = 0; i < a.Length; i++ )
            {
                System.Console.WriteLine("a["+i+"] ="+ a[i]);
            }
            foreach (int tempvar in a)
            {
                System.Console.WriteLine(tempvar);
            }
            // initialize array and then assign values
            System.Console.WriteLine("---------- assign array values");
            int[] xx = new int[6];
            xx[0] = 10;
            xx[3] = 50;
            foreach (int z in xx)
            {
                System.Console.WriteLine(z);
            }
            // manipulate text
            System.Console.WriteLine("----------- manipulate text");
            string c = "David Beckham";
            System.Console.WriteLine("Hello " + c);
            System.Console.WriteLine(c.ToUpper()); // DAVID BECKHAM
            System.Console.WriteLine(c.Substring(2));//vid Beckham
            System.Console.WriteLine(c.Substring(4,5));//d Bec
            System.Console.WriteLine(c.IndexOf("v"));//2
            System.Console.WriteLine(c[1]);//a
            // text array
            string[] cy = {"one", "two", "three" };
            foreach (string z in cy)
            {
                System.Console.WriteLine(z);
            }
            // change text to number
            System.Console.WriteLine("--------  change text to number");
            string age = "34";
            string sal = "8743784.71";
            int g = System.Convert.ToInt32(age);
            System.Console.WriteLine("g/2= " + g/2);
            System.Console.WriteLine("sal*0.02= " + System.Convert.ToDouble(sal)* .02);


            // End of program
            System.Console.ReadLine();


        }
    }
}