Introduction to C#

Basic Introduction to the C# Programming Language

Updated: 03 September 2023

From the Microsoft Virtual Academy

Hello World

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace HelloWorld
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{
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class Program
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{
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static void Main(string[] args)
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{
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Console.WriteLine("Hello, World!");
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Console.ReadLine();
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}
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}
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}

Variables

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Variables
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{
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class Program
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{
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static void Main(string[] args)
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{
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Console.WriteLine("Some Math here : ");
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int x;
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int y;
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x = 7;
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y = x + 3;
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Console.WriteLine("x = 7");
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Console.WriteLine("y = x + 3");
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Console.WriteLine("y = " + y);
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Console.ReadLine();
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//-------------------------------------------
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Console.WriteLine("What is your name?");
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Console.Write("Type your first name : ");
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string MyFirstName = Console.ReadLine();
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Console.Write("Type your last name : ");
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string MyLastName = Console.ReadLine();
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Console.WriteLine("Hello, " + MyFirstName + " " + MyLastName + " !");
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Console.ReadLine();
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}
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}
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}

Decisions

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Decisions
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{
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class Program
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{
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static void Main(string[] args)
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{
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Console.WriteLine("Bob's Big Giveaway");
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Console.Write("Choose a Door : 1,2 or 3 : ");
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string Selection = Console.ReadLine();
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string Prize;
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if (Selection == "1")
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Prize = "You Win a Car";
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else if (Selection == "2")
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Prize = "You Win a Goat";
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else if (Selection == "3")
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Prize = "You Win a bag of weed";
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else
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{
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Prize = "nada Bruv";
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Prize += ", You Lose";
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}
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//----------------------------------------------
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Console.WriteLine(Prize);
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Console.ReadLine();
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Console.WriteLine("Bob's Big Giveaway Part 2");
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Console.Write("Choose a Door : 1,2 or 3 : ");
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string Selection2 = Console.ReadLine();
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string Prize2 = (Selection2 == "1") ? "Boat" : "Bale of Hay";
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Console.WriteLine("You chose {0}, you Win a {1}", Selection2, Prize2);
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Console.ReadLine();
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}
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}
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}

For Loops

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace ForIteration
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{
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class Program
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{
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static void Main(string[] args)
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{
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for (int i = 0; i < 10; i++) // For loop, create variable; stop condition; increase value by one
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{
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Console.WriteLine(i);
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if (i == 7)
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{
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Console.WriteLine("Found Seven");
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break; // Breaks out of for loop
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}
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}
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Console.ReadLine();
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}
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}
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}

While Loop

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace WhileIteration
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{
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class Program
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{
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static void Main(string[] args)
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{
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do
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{
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Console.Clear();
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} while (MenuOptions());
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}
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private static bool MenuOptions()
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{
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Console.WriteLine("Choose an Option:");
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Console.WriteLine("1. Write stuff");
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Console.WriteLine("2. Random Int");
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Console.WriteLine("3. Exit");
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string result = Console.ReadLine();
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if (result == "1")
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{
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Console.WriteLine("Write stuff for me to write");
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string input = Console.ReadLine();
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while (input != "")
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{
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Console.WriteLine("You Said {0}", input);
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input = Console.ReadLine();
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}
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return true;
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}
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else if (result == "2")
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{
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Random MyRandom = new Random();
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int RandomNum = MyRandom.Next(0, 10);
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Console.WriteLine("Guess the Int");
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bool correct;
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do
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{
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string guess = Console.ReadLine();
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if (guess == RandomNum.ToString())
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{
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correct = true;
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Console.WriteLine("Correct!");
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Console.WriteLine("Click Enter to end");
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}
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else
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{
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correct = false;
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Console.WriteLine("Incorrect");
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}
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} while (correct == false);
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Console.ReadLine();
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return true;
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}
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else if (result == "3")
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{
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return false;
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}
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else
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{
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return true;
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}
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}
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}
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}

Arrays

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace Arrays
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{
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class Program
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{
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static void Main(string[] args)
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{
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int[] nums = new int[5];
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nums[0] = 4;
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nums[1] = 5;
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nums[2] = 8;
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nums[3] = 43;
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nums[4] = 91;
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Console.WriteLine(nums[3]);
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int len = nums.Length;
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Console.WriteLine(len);
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int[] vals = new int[] { 1, 2, 2, 8, 3, 12, 54 };
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for (int i = 0; i < vals.Length; i++) //manually iterate through values
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{
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Console.WriteLine(vals[i]);
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}
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string[] words = new string[] { "hey", "man", "wassup" };
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foreach (string word in words) //automatically iterate through items
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{
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Console.WriteLine(word);
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}
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// we can create a string and make it an array of characters
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string me = "Nabeel Valley"; //make string
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char[] mechars = me.ToCharArray(); //convert to CharArray
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Array.Reverse(mechars); //reverse array values
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foreach (char mechar in mechars)
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{
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Console.Write(mechar);
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}
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Console.ReadLine();
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}
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}
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}

Functions

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace SimpleMethod
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{
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class Program
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{
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static void Main(string[] args)
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{
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string message = "Hello World";
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PrintStuff(message);
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PrintStuff("Hey who are you?");
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string name = Console.ReadLine();
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string[] PrintWords = new string[] { "Hello", name };
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PrintStuff(JoinWords("Hello", name)); //uses method singnature for two inputs
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PrintStuff(JoinWords(PrintWords)); //uses method signature for array input
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Console.ReadLine();
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}
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private static void PrintStuff(string text)
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{
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Console.WriteLine(text);
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}
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private static string JoinWords(string word1, string word2)//two string joiner
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{
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return (word1 + " " + word2);
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}
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private static string JoinWords(string[] words)//array string joiner
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{
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string newstring = "";
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foreach (string word in words)
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{
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newstring += word + " ";
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}
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return newstring;
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}
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}
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}