C# Methods, Built-in .NET Classes, Arrays, Lists, Dictionary

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net;

class DemoLive
{
    static void Main()
    {
        /*
        // int[] myArray;
        // int[] myArray = new int[5];
        //int[] myArray = new int[3] { 1, 2, 3 };
        int[] myArray = { 1, 2, 3};

        myArray[1] = 120;

        for (var i = 0; i < myArray.Length; i++)
        {
            Console.WriteLine(myArray[i]);
        }

        Console.WriteLine(myArray.Sum());
        Console.WriteLine(myArray.Min());
        Console.WriteLine(myArray.Max());
        Console.WriteLine(myArray.First<int>());
        Console.WriteLine(myArray.Last<int>());
        */

        /*
        string[] ourNames = { "Stoyan", "Ivan", "Petko" };
        ourNames[1] = "Zweda";

        foreach (string name in ourNames)
        {
            Console.WriteLine(name);
        }
        */
        /*
        int[,] my2DimensionsArray;
        // Ask the user for the size
        int width = int.Parse(Console.ReadLine());
        int height = int.Parse(Console.ReadLine());
        my2DimensionsArray = new int[width, height];
        */
        /*
        // int[,] my2DimensionsArray = new int[3, 3];
        int[,] my2DimensionsArray = new int[3, 3] {
            {1,2,3 },
            {1,2,3 },
            {1,2,3 }
        };

        my2DimensionsArray[0, 1] = 120;

        for(var i = 0; i < my2DimensionsArray.GetLength(0); i++)
        {
            for (var j=0; j< my2DimensionsArray.GetLength(1); j++)
            {
                Console.Write("{0,10}",my2DimensionsArray[i,j]);
            }
            Console.WriteLine();
        }
        */
        /*
        int[,,] my3DimensionsArray = new int[3,3,3]
        {
            { {1,2,3 }, { 1,2,3 }, {1,2,3 } },
            { {1,2,3 }, { 1,2,3 }, {1,2,3 } },
            { {1,2,3 }, { 1,2,3 }, {1,2,3 } }
        };
        */
        /*
        int[][] myArrayOfArrays = {
            new int[2] {1,2},
            new int[3] {1,2,3},
            new int[4] {1,2,3,4},
            new int[2] {1,2}
        };
        */
        /*
        int width = 4, height = 6;
        string[,] matrix =
          new string[height, width];
        for (int row = 0; row < height; row++)
        {
            for (int col = 0; col < width; col++)
            {
                matrix[row, col] = "" +
                  (char)('a' + row) +
                  (char)('a' + col);
            }
        }

        for (int row = 0; row < height; row++)
        {
            for (int col = 0; col < width; col++)
            {
                Console.Write("{0,10}",matrix[row, col]);
            }
            Console.WriteLine();
        }
        */
        /*
        for (int i = 0; i < 10; i++)
        {
            //for (var j = 0; j < i; j++)
            //{
            //    Console.Write("-");
            //}
            // PrintHyphens(i, 2,3,4,4);
            PrintHyphens(3, j : i);
            Console.WriteLine();
        }
    }

    public static void PrintHyphens(int t, int n =10, int j = 4) //  params int[] myParams)
    {
        for (var j = 0; j < n; j++)
        {
            // Console.Write("{0}, {1}", 2,3);
            Console.Write("-");
        }
        */
        /*
        Console.WriteLine(CalcTriangleArea(2.3, 4.5));
        Console.WriteLine(CalcTriangleArea(10, 4.5));
        Console.WriteLine(CalcTriangleArea(23, 4.5));
        */
        /*
        DateTime today = DateTime.Now;
        today = today.AddDays(2);
        Console.WriteLine(today);

        double cosine =Math.Cos(Math.PI* 60 /180 );
        Console.WriteLine(cosine);
        */
        /*
        Random rnd = new Random();
        for (int i = 0; i < 10; i++)
        {
            Console.WriteLine(rnd.Next(1, 10));
        }
        */
        /*
        DateTime today = DateTime.Now;
        Console.WriteLine("Today is: " + today);
        DateTime tomorrow = today.AddDays(1);
        Console.WriteLine("Tomorrow is: " + tomorrow);
        double angleDegrees = 60;
        double angleRadians = angleDegrees * Math.PI / 180;
        Console.WriteLine(Math.Cos(angleRadians));
        Random rnd = new Random();
        Console.WriteLine(rnd.Next(1, 100));
        WebClient webClient = new WebClient();
        webClient.DownloadFile("http://example.com", "file.txt");
        Process.Start("file.txt");
        */

        /*
        List<int> numbers = new List<int>();
        numbers.Add(1);
        numbers.Add(2);
        numbers.Add(3);

        for (int i = 0; i < numbers.Count; i++)
        {
            Console.WriteLine(numbers[i]);
        }
        */
        /*
        List<string> names =
    new List<string>() { "Peter", "Maria", "Katya", "Todor" };
        names.Add("Nakov"); // Peter, Maria, Katya, Todor, Nakov
        names.RemoveAt(0); // Maria, Katya, Todor, Nakov
        names.Insert(3, "Sylvia"); // Maria, Katya, Todor, Sylvia, Nakov
        names[1] = "Michael"; // Maria, Michael, Todor, Sylvia, Nakov
        foreach (var name in names)
        {
            Console.WriteLine(name);
        }
        */
        /*
        Dictionary<string, string> phonebook = new Dictionary<string, string>();
        phonebook["John Smith"] = "+1-555-8976";
        phonebook["Lisa Smith"] = "+1-555-1234";
        phonebook["Sam Doe"] = "+1-555-5030";
        phonebook["Nakov"] = "+359-899-555-592";
        phonebook["Nakov"] = "+359-2-981-9819";
        phonebook.Remove("John Smith");
        foreach (var pair in phonebook)
        {
            Console.WriteLine("{0} --> {1}", pair.Key, pair.Value);
        }
        */
        /*
        Dictionary<DateTime, string> events =
    new Dictionary<DateTime, string>();
        events[new DateTime(1998, 9, 4)] = "Google's birth date";
        events[new DateTime(2013, 11, 5)] = "SoftUni's birth date";
        events[new DateTime(1975, 4, 4)] = "Microsoft's birth date";
        events[new DateTime(2004, 2, 4)] = "Facebook's birth date";
        events[new DateTime(2013, 11, 5)] =
            "Nakov left Telerik Academy to establish SoftUni";
        foreach (var entry in events)
        {
            Console.WriteLine("{0:dd-MMM-yyyy}: {1}",
                entry.Key, entry.Value);
        }
        */
        /*
        string str = "SoftUni";
        Console.WriteLine(str);
        for (int i = 0; i < str.Length; i++)
        {
            Console.WriteLine("str[{0}] = {1}", i, str[i]);
        }
        Console.WriteLine(str.IndexOf("Uni")); // 4
        Console.WriteLine(str.IndexOf("uni")); // -1 (not found)
        Console.WriteLine(str.Substring(4, 3)); // Uni
        Console.WriteLine(str.Replace("Soft", "Hard")); // HardUni
        Console.WriteLine(str.ToLower()); // softuni
        Console.WriteLine(str.ToUpper()); // SOFTUNI
        */
        /*
        string firstName = "Steve";
        string lastName = "Jobs";
        int age = 56;
        Console.WriteLine(firstName + " " + lastName +
          " (age: " + age + ")"); // Steve Jobs (age: 56)
        string allLangs = "C#, Java; HTML, CSS; PHP, SQL";
        string[] langs = allLangs.Split(new char[] { ',', ';', ' ' },
          StringSplitOptions.RemoveEmptyEntries);
        foreach (var lang in langs)
            Console.WriteLine(lang);
        Console.WriteLine("Langs = " + string.Join(", ", langs));
        Console.WriteLine("  \n\n Software  University  ".Trim());
        */

        Person[] persons = new Person[2];

        Person stoyan = new Person();
        stoyan.Name = "Stoyan";
        stoyan.Age = 52;

        Person mariya = new Person();
        mariya.Name = "Mariya";
        mariya.Age = 20;

        // Console.WriteLine("is am a human. My name is {0}. I am {1} years old!", stoyan.Name, stoyan.Age);
        // Console.WriteLine("is am a human. My name is {0}. I am {1} years old!", mariya.Name, mariya.Age);

        stoyan.Introduce();
        mariya.Introduce();

        persons[0] = stoyan;

    }

    public static double CalcTriangleArea(double width, double height)
    {
        return width * height / 2;
    }
}