Use the Math.BigMul() method to find the product of two 32-bit numbers.The following are our two numbers.int one = 345272828; int two = 887685744;Now, get the product.long res; res = Math.BigMul(one, two);Example Live Demousing System; using System.Globalization; class Demo {    static void Main() {       int one = 345272828;       int two = 887685744;       long res;       res = Math.BigMul(one, two);       Console.WriteLine("{0} * {1} = {2}", one, two, res);    } }Output345272828 * 887685744 = 306493767206164032

Use the First() method to get the first element from an array.Firstly, set an array.int[] arr = {20, 40, 60, 80 , 100};Now, use the Queryable First() method to return the first element.arr.AsQueryable().First();The following is the entire example.Example Live Demousing System; using System.Linq; using System.Collections.Generic; class Program {    static void Main() {       int[] arr = {20, 40, 60, 80 , 100};       // getting the first element       int res = arr.AsQueryable().First();       Console.WriteLine(res);    } }Output20

The Sortable standard format specifier represents a custom date and time format string.The format string is defined by the DateTimeFormatInfo.SortableDateTimePattern property.The custom format string.yyyy'-'MM'-'dd'T'HH':'mm':'ssExample Live Demousing System; class Demo {    static void Main() {       DateTime date = new DateTime(2018, 9, 5, 2, 12, 40);       Console.WriteLine(date.ToString("s"));    } }Output2018-09-05T02:12:40

The ElementAt() method in C# to get elements at specified index position.Firstly, set the string array.string[] str = { "Jack", "Pat", "David"};Now, to get the element at a particular index, use the ElementAt() method as shown in the following example −Example Live Demousing System.IO; using System; using System.Linq; class Program {    static void Main() {       string[] str = { "Jack", "Pat", "David"};       Random r = new Random(DateTime.Now.Second);       // to generate random string       string res = str.AsQueryable().ElementAt(r.Next(0, str.Length));       Console.WriteLine("Random Name = '{0}'", res);    } }OutputRandom Name = 'Jack'

Get the difference between two arrays using the Except() method.The following are the two arrays.int[] arr = { 9, 12, 15, 20, 35, 40, 55, 67, 88, 92 }; int[] arr2 = { 20, 35 };To get the difference, use Except() method that returns the first list, except the elements in the second list.arr.AsQueryable().Except(arr2);The following is the entire example.Example Live Demousing System; using System.Linq; using System.Collections.Generic; class Program {    static void Main() {       int[] arr = { 5, 10, 15, 20, 35, 40 };       int[] except = { 20, 35 };       ... Read More

FomatException is thrown when the format of an argument is invalid.Let us see an example.When we set a value other than int to int.Parse() method, then FormatException is thrown as shown below −Example Live Demousing System; class Demo {    static void Main() {       string str = "3.5";       int res = int.Parse(str);    } }The following error is thrown when the above program is compiled since we have passed a value other than integer.OutputUnhandled Exception: System.FormatException: Input string was not in a correct format.

To get the size of a 3D array in C#, use the GetLength() method with parameter as the index of the dimensions.GetLength(dimensionIndex)To get the size.arr.GetLength(0) arr.GetLength(1) arr.GetLength(2)Example Live Demousing System; class Program {    static void Main() {       int[,,] arr = new int[3,4,5];       // length of a dimension       Console.WriteLine(arr.GetLength(0));       Console.WriteLine(arr.GetLength(1));       Console.WriteLine(arr.GetLength(2));       // length       Console.WriteLine(arr.Length);    } }Output3 4 5 60

BinarySearch() works on a sorted list whether its numeric, alphanumeric or strings. It finds you the index of an element.Let’s say the following is our list.List list = new List(); list.Add(70); list.Add(150); list.Add(220); list.Add(250); list.Add(300);Now to check the index where 250 is placed, use BinarySearch() method.list.BinarySearch(250);Example Live Demousing System; using System.Collections.Generic; class Demo {    static void Main() {       List list = new List();       list.Add(70);       list.Add(150);       list.Add(220);       list.Add(250);       list.Add(300);       int value = list.BinarySearch(250);       Console.WriteLine("Element 250 at Index: "+value);    } }OutputElement 250 at Index: 3

The "." custom format specifier adds a localized decimal separator into the output string.The 1st period in the format string determines the location of the decimal separator in the formatted value.double d = 2.3; d.ToString("0.00", CultureInfo.InvariantCultureLet us see another example to learn how to implement “.” Custom specifier.Example Live Demousing System; using System.Globalization; class Demo {    static void Main() {       double d;       d = 3.7;       Console.WriteLine(d.ToString("0.00", CultureInfo.InvariantCulture));       Console.WriteLine(String.Format(CultureInfo.InvariantCulture, "{0:0.00}", d));       d = 5.89;       Console.WriteLine(d.ToString("00.00", CultureInfo.InvariantCulture));       Console.WriteLine(String.Format(CultureInfo.InvariantCulture, "{0:00.00}", d));    } }Output3.70 3.70 05.89 05.89

Firstly, set a Dictionary collection with elements.Dictionary d = new Dictionary() {    {1, "Applianes"},    {2, "Clothing"},    {3, "Toys"},    {4, "Footwear"},    {5, "Accessories"} };Now, let’s say you need to check whether key 5 exists or not. For that, use ContainsKey() method. It returns True if key is found.d.ContainsKey(5);Let us see the complete code.Example Live Demousing System; using System.Collections.Generic; public class Program {    public static void Main() {       Dictionary d = new Dictionary() {          {1, "Electronics"},          {2, "Clothing"},          {3, "Toys"},     ... Read More