Firstly, create a file using StreamWriter class and add content to it −using (StreamWriter sw = new StreamWriter("hello.txt")) {    sw.WriteLine("This is demo line 1");    sw.WriteLine("This is demo line 2");    sw.WriteLine("This is demo line 3"); }Now use the ReadAllLines() method to read all the lines. With that, the Length property is to be used to get the count of lines −int count = File.ReadAllLines("hello.txt").Length;Here is the complete code −Example Live Demousing System; using System.Collections.Generic; using System.IO; public class Program {    public static void Main() {       using (StreamWriter sw = new StreamWriter("hello.txt")) {       ... Read More

To compare, ignoring case, use the case-insensitive Dictionary.While declaring a Dictionary, set the following property to get case-insensitive Dictionary −StringComparer.OrdinalIgnoreCaseAdd the property like this −Dictionary dict = new Dictionary (StringComparer.OrdinalIgnoreCase);Here is the complete code −Example Live Demousing System; using System.Collections.Generic; public class Program {    public static void Main() {       Dictionary dict = new Dictionary       (StringComparer.OrdinalIgnoreCase);       dict.Add("cricket", 1);       dict.Add("football", 2);       foreach (var val in dict) {          Console.WriteLine(val.ToString());       }       // case insensitive dictionary i.e. "cricket" is equal to "CRICKET"       Console.WriteLine(dict["cricket"]);       Console.WriteLine(dict["CRICKET"]);    } }Output[cricket, 1] [football, 2] 1 1

Firstly, set the Dictionaries to be combined −Dictionary dict1 = new Dictionary (); dict1.Add("one", 1); dict1.Add("Two", 2); Dictionary dict2 = new Dictionary (); dict2.Add("Three", 3); dict2.Add("Four", 4);Now, use HashSet to combine them. The method used for the same purpose is UnionWith() −HashSet hSet = new HashSet (dict1.Keys); hSet.UnionWith(dict2.Keys);The following is the complete code −Example Live Demousing System; using System.Collections.Generic; public class Program {    public static void Main() {       Dictionary dict1 = new Dictionary ();       dict1.Add("one", 1);       dict1.Add("Two", 2);       Dictionary ... Read More

Use the ContainsValue() method in C# to search for a value in a Dictionary.Create a Dictionary and add elements −Dictionary d = new Dictionary(); d.Add("keyboard", "One"); d.Add("mouse", "Two");Now, use the ContainsValue() method to find a particular value −d.ContainsValue("Two");The following is the complete code −Example Live Demousing System; using System.Collections.Generic; using System.Linq; class Program {    static void Main() {       Dictionary d = new Dictionary();       d.Add("keyboard", "One");       d.Add("mouse", "Two");       // search for a value       Console.WriteLine(d.ContainsValue("Two"));    } }OutputTrue

The ToDictionary method is an extension method in C# and converts a collection into Dictionary.Firstly, create a string array −string[] str = new string[] {"Car", "Bus", "Bicycle"};Now, use the Dictionary method to convert a collection to Dictionary −str.ToDictionary(item => item, item => true);Here is the complete code −Example Live Demousing System; using System.Collections.Generic; using System.Linq; class Demo {    static void Main() {       string[] str = new string[] {"Car", "Bus", "Bicycle"};       // key and value under ToDictionary       var d = str.ToDictionary(item => item, item => true);       foreach (var ele ... Read More

Set a list −List myList = new List() {    5,    10,    17,    19,    23,    33 };Let us say you need to find an element that is divisible by 2. For that, use the Find() method −int val = myList.Find(item => item % 2 == 0);Here is the complete code −Example Live Demousing System; using System.Collections.Generic; using System.Linq; class Demo {    static void Main() {       List myList = new List() {          5,          10,          17,          19,          23,          33       };       Console.WriteLine("List: ");       foreach(int i in myList) {          Console.WriteLine(i);       }       int val = myList.Find(item => item % 2 == 0);       Console.WriteLine("Element that divides by zero: "+val);    } }OutputList: 5 10 17 19 23 33 Element that divides by zero: 10

Use the Skip() method in C# to skip number of elements in an array.Let’s say the following is our array −int[] arr = { 10, 20, 30, 40, 50 };To skip the first two elements, use the Skip() method and add argument as 2 −arr.Skip(2);Let us see an example −Example Live Demousing System.IO; using System; using System.Linq; public class Demo {    public static void Main() {       int[] arr = { 10, 20, 30, 40, 50 };       Console.WriteLine("Initial Array...");       foreach (var res in arr) {          Console.WriteLine(res);     ... Read More

The All() extension method is part of the System.Linq namepspace. Using this method, you can check whether all the elements match a certain condition or not.Set an array −int[] arr = { 6, 7, 15, 40, 55 };The following is an example. It checks whether all the elements in the array is greater than and equal to 2 or not −arr.All(element => element > = 2);Here is the complete code −Example Live Demousing System; using System.Linq; class Program {    static void Main() {       int[] arr = { 6, 7, 15, 40, 55 };       bool res = arr.All(element => element >= 2);       Console.WriteLine(res);    } }OutputTrue

Use the Aggregate method in C# to perform mathematical operations such as Sum, Min, Max, Average, etc.Let us see an example to multiply array elements using Aggregate method.Here is our array −int[] arr = { 10, 15, 20 };Now, use Aggregate() method −arr.Aggregate((x, y) => x * y);Here is the complete code −Example Live Demousing System; using System.Linq; using System.IO; public class Demo {    public static void Main() {       int[] arr = { 10, 15, 20 };       // Multiplication       int res = arr.Aggregate((x, y) => x * y);       Console.WriteLine(res);    } }Output3000

With the TakeWhile() method, you can get methods by setting a condition base on Predicate.Firstly, declare and initialize an array −int[] arr = { 25, 40, 65, 70};Now, use the TakeWhile() method and predicate to get all the elements that are less than 30.var val = arr.TakeWhile(ele => ele < 30);Let us see the same example, wherein we have displayed the values less than 30 using Predicate −Example Live Demousing System; using System.Linq; using System.IO; public class Demo {    public static void Main() {       int[] arr = { 25, 40, 65, 70};       var val = arr.TakeWhile(ele => ele < 30);       foreach (int res in val) {          Console.WriteLine(res);       }    } }Output25