Task and Task of T types in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple Task returning a string

What is the output of this C# program when run?

C Sharp (C#)

using System;
using System.Threading.Tasks;

class Program {
    static async Task Main() {
        Task<string> task = Task.FromResult("Hello World");
        string result = await task;
        Console.WriteLine(result);
    }
}

A Hello World

B Task`1

C System.Threading.Tasks.Task

D Compilation error

💡 Hint

Remember that Task.FromResult creates a completed Task with the given result.

The Task.FromResult method returns a completed Task with the specified result. Awaiting it returns the string "Hello World", which is printed.

❓ Predict Output

intermediate

Value of Task after delay

What will be the output of this program?

C Sharp (C#)

using System;
using System.Threading.Tasks;

class Program {
    static async Task Main() {
        Task<int> task = GetNumberAsync();
        int value = await task;
        Console.WriteLine(value);
    }

    static async Task<int> GetNumberAsync() {
        await Task.Delay(100);
        return 42;
    }
}

A Task`1

B 0

C 42

D Runtime exception

💡 Hint

The method returns 42 after a short delay.

The async method GetNumberAsync returns 42 after awaiting a delay. Awaiting the Task returns 42, which is printed.

❓ Predict Output

advanced

What happens when awaiting a non-generic Task?

Consider this code snippet. What is printed when it runs?

C Sharp (C#)

using System;
using System.Threading.Tasks;

class Program {
    static async Task Main() {
        Task task = Task.Delay(50);
        await task;
        Console.WriteLine("Done");
    }
}

A Done

B Task

C Compilation error

D Runtime exception

💡 Hint

Awaiting a Task waits for its completion but returns no value.

Awaiting a non-generic Task waits for it to complete. After the delay, "Done" is printed.

🧠 Conceptual

advanced

Difference between Task and Task

Which statement correctly describes the difference between Task and Task in C#?

A Task<T> is used only for synchronous operations, Task only for asynchronous.

B Task represents an operation that returns no value, while Task<T> represents an operation that returns a value of type T.

C Task<T> can only be awaited, Task cannot be awaited.

D Task and Task<T> are identical and interchangeable.

💡 Hint

Think about whether the operation returns a result or not.

Task is for operations that do not return a value. Task returns a value of type T when awaited.

🔧 Debug

expert

Identify the runtime error in this Task usage

What error will this code produce when run?

C Sharp (C#)

using System;
using System.Threading.Tasks;

class Program {
    static void Main() {
        Task<int> task = Task.Run(() => 10 / 0);
        Console.WriteLine(task.Result);
    }
}

A No error, prints 0

B System.DivideByZeroException

C Compilation error

D System.AggregateException

💡 Hint

Exceptions inside Tasks are wrapped when accessing Result.

The division by zero inside the Task causes a DivideByZeroException, but accessing task.Result throws an AggregateException wrapping it.