Server Side Programming Articles - Page 2545 of 2650

The async and await keyword is used in C# for asynchronous programming.An application with a GUI, check the content of the queue and if an unprocessed task is there, it takes it out and processes it first. The code executes synchronously and the unprocessed task is completed first. The application will show stop responding to messages if the processing takes more time than expected.Let us see what is discussed above −private void OnRequestDownload(object sender, RoutedEventArgs e) {    var req = HttpWebRequest.Create(_requestedUri);    var res = req.GetResponse(); }To solve the above issue, use the async and await keywords −private async ... Read More

Association in C#The association defines the relationship between an object in C#. An a one-to-one, one-to-many, many-to-one and many-to-many relationship can be defined between objects.For example, An Employee can be associated with multiple projects, whereas a project can have more than one employee.Composition in C#Under Composition, if the parent object is deleted, then the child object also loses its status.The composition is a special type of Aggregation and gives a part-of relationship.For example, A Car has an engine. If the car is destroyed, the engine is destroyed as well.Aggregation in C#Aggregation is a direct relation between objects in C#. It ... Read More

To calculate a factorial in C#, you can use any of the following three ways −Calculate factorial with for loopExampleLive Demousing System; using System.Collections.Generic; using System.Linq; using System.Text; namespace factorial {    class Test {       static void Main(string[] args) {          int i, res;          int value = 5;          res = value;          for (i = value - 1; i >= 1; i--) {             res = res * i;          }       ... Read More

The abstract class includes abstract and non-abstract methods. You cannot instantiate an abstract class.The sealed class prevents inheritance and you cannot use it as a base class.Abstract ClassesTo declare an abstract class, you need to place the keyword abstract before the class definition. An example of class members in an abstract class can be the following that defines an abstract method −public abstract class Vehicle {    public abstract void display(); }The abstract method definition is followed by a semi-colon since it has no implementation.Sealed ClassesTo declare a sealed class, you need to place the keyword sealed before the class definition. ... Read More

To add and concatenate strings in C#, use the string. Concat method. The plus operator can also be used for the same purpose of concatenation.Plus Operatorstring str2 = "Hanks" + str1;ExampleLet us see an example of + operator to concatenate strings −Live Demousing System; class Program {    static void Main() {       string str1 = "Tom";       // concatenation       string str2 = "Hanks" + str1;       Console.WriteLine(str2);    } }OutputHanksTomString.concatstring str2 = string.Concat("Hanks", str1);ExampleLet us see an example of string.concat to concatenate strings in C# −Live Demousing ... Read More

The abstract keyword in C# is used for abstract classes. An abstract class in C# includes abstract and nonabstract methods. You cannot instantiate an abstract class.Example of an abstract class Vehicle and abstract method display() −public abstract class Vehicle {    public abstract void display(); }The abstract class has derived classes: Bus, Car, and Motorcycle. The following is an implementation of the Car derived class −public class Car : Vehicle {    public override void display() {       Console.WriteLine("Car");    } }ExampleThe following is an example of abstract classes in C# −Live Demousing System; public abstract class Vehicle ... Read More

An attribute is a declarative tag that is used to convey information to runtime about the behaviors of various elements like classes, methods, structures, enumerators, assemblies etc. in your program. To set an attribute −[attribute(positional_parameters, name_parameter = value, ...)] ElementHere, the name of the attribute and values come inside [ ] positional parameters allow you to specify information.ExampleThe following is an example to access attribute and methods in C# −Live Demo#define DEBUG using System; using System.Diagnostics; public class Demo {    [Conditional("DEBUG")]    public static void Message(string str) {       Console.WriteLine(str);    } } class Test {    static ... Read More

Yes, arrays zero indexed in C#. Let us see how −If the array is empty, it has zero elements and has length 0.If the array has one element in 0 indexes, then it has length 1.If the array has two elements in 0 and 1 indexes, then it has length 2.If the array has three elements in 0, 1 and 2 indexes, then it has length 3.The following states that an array in C# begins with index 0 −/* begin from index 0 */ for ( i = 0; i < 5; i++ ) {    n[ i ] = ... Read More

Assert statements are an effective way to catch program logic errors at runtime. It has two arguments −A boolean expression for a true condition, andWhat to display in case of false.Assertions are useful in large and complex programs to quickly flush out errors that generally arise when the code is modified. Avoid using any function call inside the assert method.You need to be sure that whatever code you add inside an Assert should not change the output if it is removed. This is when you implement Debug. Assert in your program.To implement it, you can use a temporary variable −int ... Read More

A resizable implementation of the List interface is called ArrayList. It is a non-generic type of collection in C# that dynamically resizes.Let us see how to initialize ArrayList in C# −ArrayList arr= new ArrayList();Add an element like the below-given code snippet −ArrayList arr1 = new ArrayList(); arr1.Add(120); arr1.Add(160);Let us see the complete example to implement ArrayList in C# −ExampleLive Demousing System; using System.Collections; public class MyClass {    public static void Main() {       ArrayList arr1 = new ArrayList();       arr1.Add(120);       arr1.Add(160);       ArrayList arr2 = new ArrayList();   ... Read More