What is async and await?
💡 Concept: async and await
Async and await are keywords in C# that enable writing asynchronous code in a readable and maintainable way.
📘 Quick Intro
They allow methods to run asynchronously without blocking the main thread, improving responsiveness.
🧠 Analogy
Imagine placing an order and continuing other tasks without waiting for the delivery to arrive; async-await lets your program do the same.
🔧 Technical Explanation
- ⏳ The async modifier marks a method as asynchronous.
- ⏭️ The await keyword pauses execution until the awaited Task completes.
- 🧵 Enables non-blocking I/O operations.
- ⚙️ Works with Task and Task<T> types.
- 🔄 Improves scalability and UI responsiveness.
🎯 Use Cases
- ✅ Performing I/O-bound operations asynchronously.
- ✅ Keeping UI responsive during background tasks.
- ✅ Implementing scalable web applications.
- ✅ Avoiding thread blocking in server-side code.
💻 Code Example
public async Task GetDataAsync() {
await Task.Delay(1000);
return 42;
}
public async Task UseDataAsync() {
int result = await GetDataAsync();
Console.WriteLine($""Result: {result}"");
}
❓ Interview Q&A
Q1: What does async keyword do?
A: Marks a method as asynchronous.
Q2: What is the purpose of await?
A: Pauses method execution until Task completes.
Q3: Can async methods return void?
A: Only event handlers.
Q4: Does async create new threads?
A: No, it doesn't create threads but enables asynchronous execution.
Q5: What is Task in async?
A: Represents ongoing work.
Q6: How does async improve UI apps?
A: Prevents blocking the UI thread.
Q7: Can async methods be awaited?
A: Yes, to get result or continue.
Q8: What happens if you forget await?
A: Task runs but exceptions may be unhandled.
Q9: Is async suitable for CPU-bound tasks?
A: Typically no, use parallelism instead.
Q10: What namespace is async part of?
A: System.Threading.Tasks.
📝 MCQs
Q1. What does async keyword do?
- Blocks execution
- Marks method as asynchronous
- Creates thread
- Returns void
Q2. What is the purpose of await?
- Blocks thread
- Pauses until Task completes
- Creates new thread
- Throws error
Q3. Can async methods return void?
- Yes always
- Only event handlers
- No
- Sometimes
Q4. Does async create new threads?
- Yes
- No
- Sometimes
- Always
Q5. What is Task in async?
- Thread
- Process
- Represents ongoing work
- Event
Q6. How does async improve UI apps?
- Slows UI
- Prevents blocking UI thread
- Ignores UI
- Blocks UI
Q7. Can async methods be awaited?
- No
- Yes
- Sometimes
- Never
Q8. What happens if you forget await?
- No effect
- Exceptions unhandled
- Code won't run
- Blocks thread
Q9. Is async suitable for CPU-bound tasks?
- Yes
- No
- Sometimes
- Always
Q10. What namespace is async part of?
- System.IO
- System.Threading.Tasks
- System.Net
- System.Text
💡 Bonus Insight
Async and await simplify asynchronous programming, making code easier to write, read, and maintain.
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