Multiple catch blocks in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of multiple catch blocks in C#?

Multiple catch blocks allow a program to handle different types of exceptions separately, providing specific responses for each error type.

beginner

How does C# decide which catch block to execute when an exception occurs?

C# checks each catch block in order and executes the first one that matches the type of the thrown exception or its base types.

intermediate

Can you have a general catch block after specific ones? Why?

Yes, a general catch block (catch without specifying an exception type) can be placed last to catch any exceptions not handled by previous specific catch blocks.

intermediate

What happens if no catch block matches the thrown exception?

If no catch block matches, the exception propagates up the call stack, potentially causing the program to terminate if unhandled.

beginner

Show a simple example of multiple catch blocks in C#.

try { int[] numbers = {1, 2, 3}; Console.WriteLine(numbers[5]); } catch (IndexOutOfRangeException) { Console.WriteLine("Index is out of range."); } catch (Exception) { Console.WriteLine("Some other error occurred."); }

What is the order of catch blocks when handling exceptions?

A From most general to most specific exception types

B Alphabetical order by exception name

C Random order

D From most specific to most general exception types

Catch blocks should be ordered from most specific exceptions to most general to ensure the correct handler is executed.

What happens if a catch block for Exception is placed before a catch block for IndexOutOfRangeException?

A The program will crash

B Both catch blocks will execute

C The IndexOutOfRangeException catch block will never be reached

D The compiler will reorder the catch blocks automatically

The general Exception catch block will catch all exceptions including IndexOutOfRangeException, so the specific catch block after it is unreachable.

Can you have multiple catch blocks for the same exception type?

A Yes, but only if they have different variable names

B No, each exception type can only appear once in catch blocks

C Yes, catch blocks can be duplicated freely

D Only if they are inside different try blocks

You cannot have multiple catch blocks for the same exception type in the same try statement.

What is the role of a catch block without an exception type?

A It catches any exception not caught by previous catch blocks

B It catches only null reference exceptions

C It is invalid syntax

D It catches exceptions only in debug mode

A catch block without an exception type acts as a general catch-all for any exceptions not previously caught.

If an exception is thrown but no catch block matches, what happens?

A The exception propagates up the call stack

B The program ignores the exception

C The program automatically retries the operation

D The exception is silently logged and discarded

If no catch block matches, the exception moves up to the calling method to be handled or cause program termination.

Explain how multiple catch blocks work in C# and why their order matters.

Think about how you would catch different problems separately and why catching general problems first might cause issues.

Write a simple C# try-catch example with at least two catch blocks for different exceptions.

Use exceptions like IndexOutOfRangeException and Exception for general errors.