What is C# - Interactive Quiz & Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "Hello, World!" in C#.

C Sharp (C#)

using System;

class Program {
    static void Main() {
        Console.[1]("Hello, World!");
    }
}

Drag options to blanks, or click blank then click option'

ADisplay

BPrint

COutput

DWriteLine

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods like Print or Display which do not exist in C# Console class.

In C#, Console.WriteLine prints text to the screen with a new line.

2fill in blank

medium

Complete the code to declare an integer variable named 'age' with value 25.

C Sharp (C#)

int [1] = 25;

Drag options to blanks, or click blank then click option'

Aage

Bvalue

Cnumber

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic names like number or value instead of 'age'.

Variable names should be meaningful. Here, age is the correct variable name.

3fill in blank

hard

Fix the error in the code to correctly declare a string variable with value "C#".

C Sharp (C#)

string language = [1]C#[1];

Drag options to blanks, or click blank then click option'

A`

B"

C'

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using single quotes which are for characters, not strings.

Strings in C# must be enclosed in double quotes "".

4fill in blank

hard

Fill the blank to create a simple if statement that checks if number is greater than 10.

C Sharp (C#)

if (number [1] 10) {
    Console.WriteLine("Number is greater");
}

Drag options to blanks, or click blank then click option'

A!=

B<

C>

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using < or == which do not check for greater than.

The operator > checks if the left value is greater than the right value.

5fill in blank

hard

Fill all three blanks to declare a list of integers and add the number 5 to it.

C Sharp (C#)

List<int> numbers = new [1]<int>();
numbers.[2](5);
Console.WriteLine(numbers.[3]);

Drag options to blanks, or click blank then click option'

AList

BAdd

CCount

DArray

Attempts:

3 left

💡 Hint

Common Mistakes

Using Array instead of List.

Using wrong method names like Insert instead of Add.

Using Length instead of Count for List.

Use List to create a list, Add to add an item, and Count to get the number of items.

Practice

1. What is C# primarily used for?

easy

A. Creating animations and graphics only

B. Designing websites with HTML and CSS

C. Building software applications, especially on Windows

D. Managing databases with SQL

Solution

1. Step 1: Understand C# usage

   C# is a programming language used to build software applications.

2. Step 2: Identify platform focus

   C# is especially popular for Windows software development.

3. Final Answer:

   Building software applications, especially on Windows -> Option C

4. Quick Check:

   C# = Windows software language [OK]

Hint: Remember C# is mainly for Windows apps [OK]

Common Mistakes:

• Confusing C# with web design languages
• Thinking C# is only for databases
• Believing C# is just for graphics

2. Which of the following is the correct way to start a C# program?

easy

A. void Start() {}

B. static void Main(string[] args) {}

C. function main() {}

D. begin main() {}

Solution

1. Step 1: Identify C# program entry point

   The Main method is the standard starting point in C# programs.

2. Step 2: Check syntax correctness

   Only static void Main(string[] args) {} uses correct C# syntax with static void Main and string[] args.

3. Final Answer:

   static void Main(string[] args) {} -> Option B

4. Quick Check:

   Main method syntax = static void Main(string[] args) {} [OK]

Hint: Look for 'static void Main' to find C# entry point [OK]

Common Mistakes:

• Using JavaScript or other language syntax
• Missing 'static' keyword in Main method
• Using lowercase 'main' instead of 'Main'

3. What will the following C# code output?

using System;
class Program {
  static void Main() {
    Console.WriteLine("Hello, C#");
  }
}

medium

A. Error: Missing Main method

B. Hello C#

C. Console.WriteLine("Hello, C#");

D. Hello, C#

Solution

1. Step 1: Analyze the code output command

   The code calls Console.WriteLine with the string "Hello, C#" which prints it exactly.

2. Step 2: Confirm program runs without errors

   The Main method is correct and will print the string to the console.

3. Final Answer:

   Hello, C# -> Option D

4. Quick Check:

   Console.WriteLine prints text = Hello, C# [OK]

Hint: Console.WriteLine prints exactly what is inside quotes [OK]

Common Mistakes:

• Ignoring the comma in the output
• Thinking code prints the code line itself
• Assuming syntax error due to special characters

4. Identify the error in this C# program:

using System;
class Program {
  void Main() {
    Console.WriteLine("Hi");
  }
}

medium

A. Main method must be static

B. Console.WriteLine is misspelled

C. Missing semicolon after class declaration

D. Class name must be lowercase

Solution

1. Step 1: Check Main method declaration

   Main method must be static to run as program entry point in C#.

2. Step 2: Verify other syntax elements

   Console.WriteLine is correct, semicolons after class are not needed, class names can be uppercase.

3. Final Answer:

   Main method must be static -> Option A

4. Quick Check:

   Main method static keyword required [OK]

Hint: Main method must have 'static' keyword [OK]

Common Mistakes:

• Forgetting 'static' on Main method
• Thinking class names must be lowercase
• Assuming Console.WriteLine is incorrect

5. You want to create a simple C# program that prints "Welcome!" when run. Which of these is the best complete program?

hard

A. using System;
class Program { static void Main() { Console.WriteLine("Welcome!"); } }

B. static void Main() { Console.WriteLine("Welcome!"); }

C. class Program { void Main() { print("Welcome!"); } }

D. function Main() { Console.WriteLine("Welcome!"); }

Solution

1. Step 1: Check for complete program structure

   using System; class Program { static void Main() { Console.WriteLine("Welcome!"); } } has a class named Program and a static Main method, which is required.

2. Step 2: Verify correct output command and syntax

   Console.WriteLine is correct for printing, and the string is properly quoted.

3. Final Answer:

   using System; class Program { static void Main() { Console.WriteLine("Welcome!"); } } -> Option A

4. Quick Check:

   Complete C# program = using System; class Program { static void Main() { Console.WriteLine("Welcome!"); } } [OK]

Hint: Complete C# program needs class and static Main [OK]

Common Mistakes:

• Omitting class wrapper
• Missing static keyword on Main
• Using wrong print function