What are try, catch, finally blocks?
💡 Concept: Try, Catch, Finally Blocks
These blocks allow C# programs to handle exceptions, attempt recovery, and ensure cleanup of resources.
📘 Quick Intro
The try block encloses code that may throw exceptions, catch blocks handle those exceptions, and finally block runs code regardless of exceptions.
🧠 Analogy
Think of try as testing waters, catch as a safety net for errors, and finally as cleaning up after the test, no matter what happens.
🔧 Technical Explanation
- 🔹 try: Code that might fail is placed here.
- 🔹 catch: Handles specific or general exceptions.
- 🔹 finally: Runs cleanup code, executes always.
- 🔹 Multiple catch blocks allow handling different exceptions.
- 🔹 Finally is optional but recommended for resource cleanup.
🎯 Use Cases
- ✅ Handling file I/O operations safely.
- ✅ Managing network or database errors.
- ✅ Cleaning up resources like streams and connections.
- ✅ Ensuring code runs regardless of exceptions.
💻 Code Example
try {
int value = int.Parse(""abc"");
}
catch (FormatException ex) {
Console.WriteLine(""Input format is invalid."");
}
finally {
Console.WriteLine(""Cleanup code runs here."");
}
❓ Interview Q&A
Q1: What does the try block do?
A: Contains code that may throw exceptions.
Q2: When is finally executed?
A: Always, after try and catch.
Q3: Can you have multiple catch blocks?
A: Yes, to handle different exception types.
Q4: Is finally block mandatory?
A: No, it’s optional.
Q5: Can catch block rethrow exceptions?
A: Yes, using throw.
Q6: What happens if exception is not caught?
A: Program terminates or propagates up the stack.
Q7: Can try be used without catch?
A: No, try must have at least one catch or finally.
Q8: What is the order of execution?
A: try, catch (if exception), then finally.
Q9: Can finally change the exception?
A: No, but it can suppress exceptions.
Q10: Are exceptions performance intensive?
A: Yes, use exceptions judiciously.
📝 MCQs
Q1. What does the try block do?
- Contains risky code
- Handles exceptions
- Runs always
- Cleans up resources
Q2. When is finally executed?
- Only on success
- Only on failure
- Always after try and catch
- Never
Q3. Can there be multiple catch blocks?
- No
- Yes
- Sometimes
- No idea
Q4. Is finally block mandatory?
- Yes
- No
- Sometimes
- Always
Q5. Can catch rethrow exceptions?
- No
- Yes
- Sometimes
- Never
Q6. What happens if exception not caught?
- Program continues
- Program terminates or propagates
- Program ignores
- Program logs
Q7. Can try be without catch?
- Yes
- No
- Sometimes
- No idea
Q8. Order of execution?
- Catch, try, finally
- Try, finally, catch
- Try, catch, finally
- Finally, catch, try
Q9. Can finally change exception?
- Yes
- No
- Sometimes
- Always
Q10. Are exceptions costly?
- No
- Use judiciously
- Always costly
- Never
💡 Bonus Insight
Understanding the structure and order of try-catch-finally blocks is essential for writing reliable and maintainable C# code.
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