cshar

Question 1

What is an object in C#?

Answer 1

An object is an instance of a class. A class can have as many instances as needed. For example, Honda Civic is an instance of a Car. In real programming, Honda Civic is an object. Therefore, Honda Civic is an instance of the class Car. The Model, Type, Color, and Size properties of the Honda Civic are Civic, Honda, Red, and 4, respectively. BMW 330, Toyota Carolla, Ford 350, Honda CR4, Honda Accord, and Honda Pilot are some more examples of objects of Car.

Question 2

What is the difference between a struct and a class in C#?

Answer 2

Struct

The struct is a value type in C# and inherits from System.Value Type.
Struct is usually used for smaller amounts of data.
Struct can’t be inherited from other types.
A structure can’t be abstract.
No need to create an object with a new keyword.
Do not have permission to create any default constructor.
Class

The class is a reference type in C#, and it inherits from the System.Object Type.
Classes are usually used for large amounts of data.
Classes can be inherited from other classes.
A class can be an abstract type.
We can create a default constructor.

Question 3

What is the difference between Interface and Abstract Class in C#?

Answer 3

A class can implement any number of interfaces, but a subclass can, at most, use only one abstract class.
An abstract class can have non-abstract methods (concrete methods), while in the case of interface, all the methods have to be abstract.
An abstract class can declare or use any variables, while an interface cannot do so.
In an abstract class, all data members or functions are private by default, while in an interface, all are public; we can’t change them manually.
In an abstract class, we need to use abstract keywords to declare abstract methods; in an interface, we don’t need that.
An abstract class can’t be used for multiple inheritance, while the interface can be used for multiple inheritance.
An abstract class uses a constructor, while we don’t have any constructor in an interface.

Question 4

What is an enum in C#?

Answer 4

An enum is a value type with a set of related named constants, often called an enumerator list. The enum keyword is used to declare an enumeration. It is a primitive data type that is user-defined.

An enum type can be an integer (float, int, byte, double, etc.). But if you use it beside int, it has to be cast.

An enum is used to create numeric constants in the .NET framework. All the members of the enum are enum type. Therefore, there must be a numeric value for each enum type.

The underlying default type of the enumeration element is int. By default, the first enumerator has the value 0, and the value of each successive enumerator is increased by 1.

enum Dow {Sat, Sun, Mon, Tue, Wed, Thu, Fri};
C#Copy
Some points about enum,

Enums are enumerated data types in c#.
Enums are not for the end-user. They are meant for developers.
Enums are strongly typed constant. They are strongly typed, i.e., an enum of one type may not be implicitly assigned to an enum of another type even though the underlying value of their members is the same.
Enumerations (enums) make your code much more readable and understandable.
Enum values are fixed. Enum can be displayed as a string and processed as an integer.
The default type is int, and the approved types are byte, sbyte, short, ushort, uint, long, and ulong.
Every enum type automatically derives from System.Enum, and thus, we can use System.Enum methods on enums.
Enums are value types created on the stack, not the heap.

Question 5

What are Properties in C#?

Answer 5

In C#, a property is a member of a class that provides a way to read, write or compute the value of a private field. It exposes a public interface to access and modify the data stored in a class while allowing the class to maintain control over how that data is accessed and manipulated.

Properties are declared using the get and set accessors, which define the behavior for getting or setting the property value. The get accessor retrieves the value of the property, while the set accessor sets the value of the property. A property can have one or both accessors, depending on whether it is read-only, write-only, or read-write.

For example, consider a Person class with a private field name. Then, a property Name can be created to provide access to this field like this.

Question 6

void static public

Answer 6

Public declared variables can be accessed from anywhere in the application. Static declared variables can be accessed globally without needing to create an instance of the class. Void is a type modifier which states the method and is used to specify the return type of a method in C#.

Question 7

using

Answer 7

The ‘using’ statement can be used in order to obtain a resource for processing before automatically disposing it when execution is completed.

Question 8

serialisation

Answer 8

In order to transport an object through a network, we would need to convert it into a stream of bytes. This process is called Serialization.

Question 9

Name all the C# access modifiers.

Answer 9

Private Access Modifier - A private attribute or method is one that can only be accessed from within the class.
Public Access Modifier - When an attribute or method is declared public, it can be accessed from anywhere in the code.
Internal Access Modifier - When a property or method is defined as internal, it can only be accessible from the current assembly point of that class.
Protected Access Modifier - When a user declares a method or attribute as protected, it can only be accessed by members of that class and those who inherit it.

Question 10

What is meant by a Partial Class?

Answer 10

A partial class effectively breaks a class’s definition into various classes in the same or other source code files. A class definition can be written in numerous files, but it is compiled as a single class at runtime, and when a class is formed, all methods from all source files can be accessed using the same object. The keyword ‘partial’ denotes this.

Question 11

sealed cla

Answer 11

When a restriction needs to be placed on the class that needs to be inherited, sealed classes are created. In order to prevent any derivation from a class, a sealed modifier is used. Compile-time error occurs when a sealed class is forcefully specified as a base class.

Question 12

What is the difference between Arraylist and Array?

Answer 12

An array only has items of the same type and its size if fixed. Arraylist is similar but it does not have a fixed size.

Question 13

what is javascript

Answer 13

JavaScript is a popular web scripting language that’s used for client-side and server-side development. JavaScript can be inserted into HTML pages and executed by web browsers.

Apart from web development, it’s used in mobile app development, game development, querying databases, and more.

Question 14

List Some Key Features of JavaScript.

Answer 14

Lightweight interpreted language with object-oriented programming (OOP)
Dynamically-typed
Platform-independent
Offers client-side validation

Question 15

How Is JavaScript Different From Java?

Answer 15

While they share some letters in their names, they are not interlinked and are designed for different purposes. While Java is an OOP language, JavaScript is an OOP script. This means that JavaScript is written in text and then interpreted, and Java is compiled. In terms of apps, Java is used to create apps on devices or browsers, and JavaScript is mainly used with HTML documents and browsers.

Question 16

comments

Answer 16

For a single line of comment, you use two forward slash symbols (//) (/**/)

Question 17

The Difference Between Undeclared & Undefined Variables?

Answer 17

An undeclared variable has not been declared anywhere in the code, so said variable does not exist. If you try to read an undeclared variable, JavaScript throws an error.

An undefined variable has been declared in the program, but no value has been assigned. This means the variable exists, but its value is yet to be defined.

Question 18

Summarize the Primitive JavaScript Data Types.

Answer 18

String: Represents text, denoted by single quotes, double quotes, or backticks
Number: Represents numbers (integer & floating-point values)
BigInt: Represents very large numbers with precision
Boolean: Represents true & false values
Null: Represents empty, nothing, and unknown type of values
Symbol: Used for creating unique identifiers for objects
Undefined: When a variable is declared and not yet assigned a value

Question 19

How Can You Import All Named Exports From a JavaScript File?

Answer 19

You can use the import keyword and the asterisk (*) symbol.

Question 20

What Is NaN in JavaScript?

Answer 20

NaN, or ‘Not a Number’, indicates that JavaScript does not recognize the value as a legal number. You can check whether a value is NaN with the isNaN() function.

Question 21

What Are the Looping Structures in JavaScript?

Answer 21

For loops
While loops
Do-while loops

Question 22

How Can You Handle Exceptions With Javascript?

Answer 22

You use try…catch…finally syntax.

try statement: defines the code you want to run
catch statement: handle errors
finally statement: code you want to run regardless of any errors

Question 23

array decal

Answer 23

let myArray = newArray(‘value1’, ‘value2’,…, ‘valueN’);

Question 24

What Is a Class in JavaScript?

Answer 24

A blueprint for creating objects, which provides a way to define object methods and properties. You define these with the class keyword.

class Person {
constructor(name) {
this.name = name;
}

sayHi() {
console.log(Hi ${this.name});
}
}

const user = new Person(“Jane”);
user.sayHi(); // “Hi Jane”

Question 25

hoisting

Answer 25

Functions or variable declarations are promoted to the top of their scope no matter where they’re located within the code.

This only applies to variables declared with the var keyword, not let or const variables.

Question 26

what is a promise

Answer 26

A Promise is a proxy for a value not necessarily known when the promise is created. It allows you to associate handlers with an asynchronous action’s eventual success value or failure reason.

Question 27

callbacks

Answer 27

Callbacks are functions passed as arguments into other functions to make sure mandatory variables are available within the callback-function’s scope.

Question 28

closure

Answer 28

a function that has access to the outer scope of a function, so inner function can access outer function variables

Question 29

scope

Answer 29

Scope is the accessibility of variables, functions, and objects in some particular part of your code during runtime. In other words, scope determines the visibility of variables and other resources in areas of your code.

Question 30

What is a Cookie

Answer 30

A cookie is a piece of data that is stored on your computer to be accessed by your browser. Cookies are saved as key/value pairs. For example, you can create a cookie named username as below,

Question 31

local vs session storage

Answer 31

LocalStorage is the same as SessionStorage but it persists the data even when the browser is closed and reopened(i.e it has no expiration time) whereas in sessionStorage data gets cleared when the page session ends.

Question 32

why promise

Answer 32

Promises are used to handle asynchronous operations. They provide an alternative approach for callbacks by reducing the callback hell and writing the cleaner code.

Question 33

promise states

Answer 33

Pending: This is an initial state of the Promise before an operation begins
Fulfilled: This state indicates that the specified operation was completed.
Rejected: This state indicates that the operation did not complete. In this case an error value will be thrown.

Question 34

callback 2

Answer 34

A callback function is a function passed into another function as an argument. This function is invoked inside the outer function to complete an action. Let’s take a simple example of how to use callback function

Question 35

why callbacks needed

Answer 35

The callbacks are needed because javascript is an event driven language. That means instead of waiting for a response javascript will keep executing while listening for other events. Let’s take an example with the first function invoking an API call(simulated by setTimeout) and the next function which logs the message.

Question 36

eval

Answer 36

The eval() function evaluates JavaScript code represented as a string. The string can be a JavaScript expression, variable, statement, or sequence of statements.

Question 37

glob variables

Answer 37

Global variables are those that are available throughout the length of the code without any scope. The var keyword is used to declare a local variable but if you omit it then it will become global variable

Question 38

what r event

Answer 38

Events are “things” that happen to HTML elements. When JavaScript is used in HTML pages, JavaScript can react on these events. Some of the examples of HTML events are,

Web page has finished loading
Input field was changed
Button was clicked

Question 39

json

Answer 39

JSON (JavaScript Object Notation) is a lightweight format that is used for data interchanging. It is based on a subset of JavaScript language in the way objects are built in JavaScript.

Question 40

json stringily

Answer 40

When sending data to a web server, the data has to be in a string format. You can achieve this by converting JSON object into a string using stringify() method.

Question 41

parse json string

Answer 41

When receiving the data from a web server, the data is always in a string format. But you can convert this string value to a javascript object using parse() method.

Question 42

service

Answer 42

typescript class for http requests

Question 43

javascript get

Answer 43

bookuser= (booking: userBooking) => {

this.http.get<type>'urlcontroller'</type>

}

Question 44

javascript post