10.2 Task and Task.T

Let’s go through Task and Task<T> in C# — the foundation of asynchronous programming and parallel operations.

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📌 1. What is a Task?

• A Task represents an operation that may run in the background. The key here is that this operation may or may not be asynchronous.

• Part of the System.Threading.Tasks namespace.

• Can be used to run code asynchronously, wait for completion, or return results.

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📌 2. Task vs Task<T>

Type	Description
Task	Represents an asynchronous operation with no return value
Task<T>	Represents an asynchronous operation that returns a value of type T

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📌 3. Creating a Task

Task without return value

using System;
using System.Threading.Tasks;
 
Task task = Task.Run(() =>
{
    Console.WriteLine("Task running...");
    Task.Delay(1000).Wait(); // Simulate work
    Console.WriteLine("Task completed");
});
 
task.Wait(); // Wait for completion

• Task.Run starts the task on a thread pool thread

• Wait() blocks until task finishes

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Task with return value (Task<T>)

Task<int> task = Task.Run(() =>
{
    Task.Delay(1000).Wait(); // Simulate work
    return 42;
});
 
int result = task.Result; // Get the result
Console.WriteLine(result); // 42

• Task<T> allows returning a value from the async operation

• Access result via .Result (blocking) or await (non-blocking)

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📌 4. Using await with Tasks

async Task<int> CalculateAsync()
{
    await Task.Delay(1000); // Simulate work
    return 100;
}
 
int result = await CalculateAsync();
Console.WriteLine(result); // 100

• Preferred approach over .Result for non-blocking calls

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📌 5. Waiting for Multiple Tasks

Task<int> t1 = Task.Run(() => 10);
Task<int> t2 = Task.Run(() => 20);
 
int[] results = await Task.WhenAll(t1, t2);
Console.WriteLine($"Sum: {results[0] + results[1]}"); // Sum: 30

• Task.WhenAll waits for all tasks

• Task.WhenAny waits for the first task to complete

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📌 6. Exception Handling in Tasks

try
{
    Task task = Task.Run(() => throw new Exception("Error in task"));
    await task;
}
catch (Exception ex)
{
    Console.WriteLine($"Caught: {ex.Message}");
}

• Use try-catch around await to handle exceptions

• Exceptions in tasks propagate when awaited

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📌 7. Summary Table

Feature	Description
Task	Represents async operation, no return value
Task<T>	Represents async operation returning a value
Creation	Task.Run(() => ...)
Awaiting	await task (non-blocking)
Waiting	task.Wait() (blocking)
Multiple Tasks	Task.WhenAll, Task.WhenAny
Exception Handling	Use try-catch around await

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✅ Tip:

• Use Task for background operations

• Use Task when you need a result from asynchronous work

• Combine with async/await for clean, non-blocking code