C# fundamentals

Question 1

What is the difference between C# and .dot Net?

Answer 1

dot Net is a framework, but C# is a programming language.

Before C#, we had C++/C, where the runtime used to convert the code to the machine’s native language. i.e. when we run the code for x86 or x64, the compiler compiles the code to x86 machines.

C# will create an IL code which is machine independent and CLR will convert it to the machine dependent based on the architecture.

Question 2

Explain dot Net architecture.

Answer 2

Class is a basic block. We will group aLL classes under name spaces. we will group these name spaces under assembly. Many assembly forms an application.

Question 3

What are naming conventions avaialble?

Answer 3

Camel casing: string firstName = “Bharath”

Pascal casing string FirstName = “Bharath”

Hungarian notation: string strFistName = “Bharath;

usually in C#, const are pascal casing

Question 4

What is overflowing?

Answer 4

byte u = 255 +1 //overflow to 0

Question 5

How to delete a line?

Answer 5

ctrl+x

Question 6

How to add code snippet?

Answer 6

cw

Question 7

How to write format string?

Answer 7

console.writeline(“{0} {1} “, a, b);

Question 8

int.Parse()

Answer 8

used to convert int to string

Question 9

Why main method is static?

Answer 9

Because we can ensure that only one instance of Main can be there.

Question 10

what is static keyword?

Answer 10

public class Person{
   static string name = "bharath";
}

Person.name;

It i snot associated with this keyword

Question 11

How to create an array?

Answer 11

int[] numbers = new int[5];

numbers[0] = 1

int[] numbers = new int[5] {1,2,3,4,5}

Question 12

What is verbatin string?

Answer 12

string str = @”C:\PF”

Question 13

There are three strings. We have to add a seprator and coine it to one string?

Answer 13

STring.join(“,”)

Question 14

How to create an enum in c#?

Answer 14

public enum name{
 firstName: 1,
 middleName:2,
  lastname:3
}

to use name.FirstName;

Question 15

How to make enum as byte?

Answer 15

By default enum is of int datatype. To change it to byte:
public enum name : byte
{
 firstName: 1,
 middleName:2,
  lastname:3
}

Question 16

How to convert an object to string?

Answer 16

every object will have ToSTring .

Also Console.WriteLine explicitly converts to string

Question 17

How to convert string to an object?

Answer 17

Use Parse method.

Question 18

What is difference between struct and class?

Answer 18

struct is a value type. Since it is a value type it is stored in stack and immediatly removed from stack when it goes out of scope.

Ref type are stored in heap. GC will clear.

Question 19

How to use forEach?

Answer 19

forEach(var i in numbers)
{
}

Question 20

How to check if the string is empty?

Answer 20

String.IsNullOrWhiteSpace

Question 21

What is the correct syntax to declare a rectangular 3x5 array?

Answer 21

var arr = new int[3,5]

Question 22

What is the difference between arrays and lists?

Answer 22

Arrays are fixed in size and Lists are dynamic

Question 23

What will be the output of this code?

var numbers = new List() { 1, 2, 3, 4, 5 };
var index = numbers.IndexOf(1);

Console.WriteLine(index);

Answer 23

0

Question 24

How can access the last element in a list?

Answer 24

list[list.Count -1]

Question 25

What are the types of arrays in c#?

Answer 25

Single dimenstional array

int[] arr = new int[5] {1,2,3,45]

Multidimensional array

var arr = new int [2,4] 
{
   {1,2},
   {4,6}
}

Jagged array

var arr = new int[2][];
arr[0] = new int[4];

arr[0][2] =1

Question 26

How to get length of an array?

Answer 26

Array.length

Question 27

How to reverse an array?

Answer 27

arr.reverse()

Question 28

How to find the position of an arrray?

Answer 28

Array.IndexOf(arr, 2)

Question 29

How to clear the array

Answer 29

Array.clear(arr,0 ,2)

clear will populate with the default value.

Question 30

How to copy an array?

Answer 30

Array.Copy(src, dest, hWmany)

Question 31

How to sort an array/

Answer 31

arr.sort()

Question 32

How to create a list?

Answer 32

var listDemo = new List() {1,2,3,4,5};

Lists are generics

Question 33

How to add to list?

Answer 33

listDemo.Add()

Question 34

How to add range?

Answer 34

listDemo.AddRange(new int[5] {5,6,7});

Question 35

How to iterate the list?

Answer 35

forEach(var number in Numbers)

Question 36

forEach and for difference?

Answer 36

In forEach we cannot modify the array/list such as remove