Welcome to this new series of articles. If you are reading this, it means that you are… Practicing for an interview? Learning new things? Brushing up on what you already know?

Whatever! In this series of C# Interview Questions and Answers articles you will find all levels of experience so you can both review concepts and learn new things.

This time we will look at the 20 easiest C# interview questions and answers. Let’s get started!

What does C# stand for?

Answer

C# (pronounced as “C-sharp”) is named after a musical notation, where the “sharp” symbol indicates that a note should be played one semitone higher. It is an analogy from the programming language C++, implying that C# is an enhanced and more advanced version of the C++ language.

Which company developed C#?

Answer

Microsoft is the company that developed the C# programming language.

What type of language is C#?

Answer

C# is a high-level, multi-paradigm programming language, which means it incorporates various programming paradigms such as procedural, object-oriented, and functional programming. It is a statically-typed and managed language, meaning that variable data types are checked at compile-time and C# uses a garbage collector to manage memory.

In which year was C# released?

Answer

C# was released in the year 2000.

Can you name the creator of the C# language?

Answer

Anders Hejlsberg is the creator of the C# language. He is a prominent software engineer from Denmark who has also contributed to the development of languages like Delphi and TypeScript.

What is the keyword for adding comments in C# code?

Answer

There are two types of comments in C#:

1. Single-line comments: To create a single-line comment, use the double forward slashes (//) followed by your comment.

// This is a single-line comment

1. Multi-line comments: To create a multi-line comment, use the forward slash and asterisk(/) at the beginning and an asterisk and forward slash (/) at the end of the comment.

/* This is a
   multi-line
   comment */

What type of loop does the ‘foreach’ statement create in C#?

Answer

The ‘foreach’ statement in C# creates a loop that iterates over a collection or an array. It allows you to work with each element in the collection or array without using an index variable.

string[] names = { "John", "Jane", "Doe" };

foreach (string name in names)
{
    Console.WriteLine(name);
}

In this example, the foreach loop iterates through the “names” array and prints each name to the console.

Can you name a widely used C# Integrated Development Environment (IDE)?

Answer

Visual Studio is a widely used IDE for C# development. It is developed by Microsoft and provides numerous features and tools for efficiently developing, testing, and debugging C# programs. Some alternatives to Visual Studio include Visual Studio Code and JetBrains Rider.

What is the file extension for C# source code files?

Answer

C# source code files have the file extension “.cs”.

How do you declare a variable in C#?

Answer

To declare a variable in C#, you need to specify the datatype followed by the variable name and the assignment operator (=) if you want to initialize the variable with a value at the declaration. Here’s an example:

int age = 25;
string name = "John Doe";
bool isRegistered = true;

In this example, we declare and initialize three variables with different data types: int (integer), string (text), and bool (boolean).

What is the syntax for defining a class in C#?

Answer

A class can be defined in C# using the class keyword followed by the class name and a pair of curly braces that enclose the class definition. Here’s the general syntax for defining a class in C#:

[access_modifier] class ClassName
{
    // Class members (fields, properties, methods, events, etc.)
}

For example, to create a simple Person class, the following syntax can be used:

public class Person
{
    // Fields, properties, methods, events
}

How do you instantiate an object of a class in C#?

Answer

To instantiate an object of a class in C#, use the new keyword followed by the class name and a pair of parentheses for invoking the constructor. The general syntax for creating an object is:

ClassName objectName = new ClassName();

For example, to create an object of the Person class:

Person personObj = new Person();

What is the print() method used for in C#?

Answer

There is no print() method in C#. Instead, we use the Console.WriteLine() or Console.Write() methods to output text to the console window.

• Console.WriteLine(): Writes the specified text or variable value followed by a new line.
• Console.Write(): Writes the specified text or variable value without appending a new line.

Example:

Console.WriteLine("Hello, World!"); // Prints "Hello, World!" and moves to the next line
Console.Write("Hello, "); // Prints "Hello, " without moving to the next line
Console.WriteLine("World!"); // Prints "World!" and moves to the next line

What is the purpose of the Main() method in C#?

Answer

The Main() method in C# serves as the entry point of the application. When an application starts executing, the Main() method is the first method that gets called. It typically contains the code that starts the application and initializes its behavior.

The Main() method can be defined with different signatures, including:

static void Main();
static void Main(string[] args);
static int Main();
static int Main(string[] args);

• The method must be static and have a return type of either void or int.
• The optional string[] args parameter is used for passing command-line arguments to the application.

Example of a basic Main() method:

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Hello, World!");
    }
}

How do you create a single-line comment in C#?

Answer

To create a single-line comment in C#, use the double forward-slash //. The text following the double forward-slash on the same line will be treated as a comment and ignored by the compiler.

Example:

// This is a single-line comment
int x = 5; // This is also a single-line comment

Which keyword is used to create a function in C#?

Answer

In C#, the keyword void or a data type (like int, float, string, etc.) is used to create a function. A function is a named block of code that performs a specific task and can return a value.

Here is the general syntax for declaring a function in C#:

[access_modifier] return_type FunctionName(parameters)
{
    // Function body
}

• access_modifier: Optional. Determines the visibility of the function (e.g., public, private, protected, internal).
• return_type: The data type of the value that the function returns. Use void if the function doesn’t return any value.
• FunctionName: The name of the function.
• parameters: Optional. A list of input values (arguments) passed to the function.

Example:

public int AddTwoNumbers(int num1, int num2)
{
    return num1 + num2;
}

How do you create an array in C#?

Answer

In C#, arrays are created using the data type followed by square brackets []. To create an array, you need to specify its data type, size, and (optionally) its elements during initialization.

There are several ways to create an array in C#:

1. Declare an array and then initialize its elements:

int[] myArray = new int[5]; // Creates an array of 5 integers
myArray[0] = 1;
myArray[1] = 2;
myArray[2] = 3;
myArray[3] = 4;
myArray[4] = 5;

1. Directly initialize an array with elements:

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

1. A shorter syntax for initializing an array with elements:

int[] myArray = { 1, 2, 3, 4, 5 };

How do you initialize the value of a variable?

Answer

To initialize the value of a variable in C#, first declare it using the data type followed by the variable name. Then, assign a value using the assignment operator =.

Here’s the general syntax for initializing a variable:

data_type variable_name = value;

Examples:

int age = 30; // Initialize an integer variable
float price = 19.99f; // Initialize a float variable
string name = "John"; // Initialize a string variable

What is the base class for all C# classes?

Answer

The base class for all C# classes is the System.Object class, which is also referred to as object. Every class in C#, either directly or indirectly, inherits from the object class. When you create a new class, it implicitly inherits from object if no other base class is specified.

Example:

public class Person
{
    // Fields, properties, methods
}

In this example, the Person class implicitly inherits from the object class.

What is the format specifier for an Integer in C#?

Answer

The format specifier for an integer in C# is {index_number:D} or {index_number:Dn} where D represents the decimal format and n represents the minimum size of the integer field if you want to add leading zeroes.

The index_number indicates the position of the argument to be formatted in the list of arguments provided. To use format specifiers, include them inside the string to be formatted and pass the integer(s) to the string.Format() method or inside the interpolation brackets in an interpolated string.

Examples:

int num = 42;

string formattedString1 = string.Format("The number is {0:D}", num);
Console.WriteLine(formattedString1); // Output: "The number is 42"

string formattedString2 = string.Format("The number with leading zeroes: {0:D5}", num);
Console.WriteLine(formattedString2); // Output: "The number with leading zeroes: 00042"

string interpolatedString1 = $"The number is {num:D}";
Console.WriteLine(interpolatedString1); // Output: "The number is 42"

string interpolatedString2 = $"The number with leading zeroes: {num:D5}";
Console.WriteLine(interpolatedString2); // Output: "The number with leading zeroes: 00042"

I hope that as I said at the beginning, you have learned or brushed up on your knowledge (whatever your case may be). Follow me not to receive all the other levels of C# Interview Questions the first one!