Exception handling in async code in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch exceptions in an async method.

C Sharp (C#)

try
{
    await SomeAsyncMethod();
}
catch ([1] ex)
{
    Console.WriteLine(ex.Message);
}

Drag options to blanks, or click blank then click option'

Aint

BException

Cstring

DTask

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-exception type in the catch block.

Not using await before the async method.

You catch exceptions by specifying Exception in the catch block.

2fill in blank

medium

Complete the code to rethrow the caught exception preserving the stack trace.

C Sharp (C#)

try
{
    await SomeAsyncMethod();
}
catch (Exception ex)
{
    [1];
}

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Athrow new Exception()

Bthrow ex

Creturn

Dthrow

Attempts:

3 left

💡 Hint

Common Mistakes

Using throw ex; which loses the original stack trace.

Using return instead of throwing.

Use throw; to rethrow the exception preserving the original stack trace.

3fill in blank

hard

Fix the error in the async method signature to enable exception handling.

C Sharp (C#)

public async [1] SomeAsyncMethod()
{
    throw new Exception("Error");
}

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ATask

Bvoid

Cint

Dstring

Attempts:

3 left

💡 Hint

Common Mistakes

Using void return type which prevents awaiting and catching exceptions.

Returning non-task types from async methods.

Async methods that do not return a value should return Task to allow awaiting and exception handling.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that filters exceptions by message length.

C Sharp (C#)

var errors = new Dictionary<string, string>();
foreach (var ex in exceptions)
{
    if (ex.Message.Length [1] 10)
    {
        errors.Add(ex.Message, ex[2]);
    }
}

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A>

BMessage

C<

DInnerException

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operator.

Adding the wrong property as dictionary value.

The code filters exceptions with message length greater than 10 and adds them to the dictionary using the message as key.

5fill in blank

hard

Fill all three blanks to create a LINQ query that selects exception messages with inner exceptions.

C Sharp (C#)

var messages = exceptions.Where(ex => ex.[1] != null)
    .Select(ex => ex.[2])
    .Where(msg => msg.[3]("error", StringComparison.OrdinalIgnoreCase))
    .ToList();

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AInnerException

BMessage

CContains

DStackTrace

Attempts:

3 left

💡 Hint

Common Mistakes

Using StackTrace instead of Message.

Checking wrong property for null.

This LINQ query filters exceptions that have an inner exception, selects their messages, and filters messages containing the word "error".