Why C# and the .NET ecosystem - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of async method with Task.Delay

What is the output of this C# code snippet when run?

C Sharp (C#)

using System;
using System.Threading.Tasks;

class Program {
    static async Task Main() {
        Console.WriteLine("Start");
        await Task.Delay(1000);
        Console.WriteLine("End");
    }
}

A End

B End\nStart

C Start

D Start\nEnd

💡 Hint

Remember that await pauses the method until the delay finishes.

The program prints "Start" first, then waits 1 second due to Task.Delay, then prints "End".

🧠 Conceptual

intermediate

Why use C# with .NET for cross-platform apps?

Which reason best explains why C# with .NET is a good choice for building cross-platform applications?

A .NET provides a runtime and libraries that work on Windows, Linux, and macOS, enabling cross-platform apps.

B C# code runs only on Windows, so it is optimized for that OS.

C C# requires rewriting code for each platform separately.

D C# does not support modern programming features needed for cross-platform apps.

💡 Hint

Think about what .NET runtime offers beyond just the language.

The .NET runtime and libraries support multiple operating systems, so C# apps can run cross-platform without rewriting.

🔧 Debug

advanced

Identify the error in this C# code using LINQ

What error will this code produce when compiled or run?

C Sharp (C#)

using System;
using System.Linq;

class Program {
    static void Main() {
        var numbers = new int[] {1, 2, 3, 4};
        var result = numbers.Select(x => x > 2 ? x * 2 : 0);
        foreach(var n in result) {
            Console.WriteLine(n);
        }
    }
}

A Output: 6 8

B Runtime error: NullReferenceException

C SyntaxError: Invalid expression in lambda

D Output: 2 4 6 8

💡 Hint

Check the syntax inside the lambda expression.

The lambda uses 'x * 2 if x > 2' which is invalid syntax in C#. Conditional expressions require the ternary operator.

❓ Predict Output

advanced

Output of pattern matching with switch expression

What is the output of this C# code using pattern matching?

C Sharp (C#)

using System;

class Program {
    static void Main() {
        object obj = 42;
        string result = obj switch {
            int i when i > 50 => "Large number",
            int i => $"Number {i}",
            _ => "Unknown"
        };
        Console.WriteLine(result);
    }
}

A Unknown

B Number 42

C Large number

D Compilation error

💡 Hint

Check which pattern matches the value 42.

42 is an int but not greater than 50, so the second pattern matches and prints "Number 42".

🧠 Conceptual

expert

Why is .NET ecosystem beneficial for enterprise development?

Which statement best explains a key benefit of using the .NET ecosystem in enterprise software development?

A .NET provides a rich set of libraries, tools, and a strong community that accelerates building reliable, scalable enterprise apps.

B .NET apps cannot integrate with cloud services, which reduces complexity.

C .NET ecosystem limits developers to only one programming language, simplifying training.

D .NET requires manual memory management, giving enterprises full control over resources.

💡 Hint

Think about what enterprises need: reliability, scalability, and support.

The .NET ecosystem offers many libraries, tools, and community support that help enterprises build robust applications faster.