When clause in catch in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch only ArgumentNullException exceptions.

C Sharp (C#)

try {
    string s = null;
    Console.WriteLine(s.Length);
} catch (ArgumentNullException [1]) {
    Console.WriteLine("Null argument caught.");
}

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

Awhen (false)

Bwhen (true)

Cwhen (ex != null)

Dwhen (ex is ArgumentNullException)

Attempts:

3 left

💡 Hint

Common Mistakes

Using when (false) which never catches exceptions.

The when clause with true means the catch block will always execute for ArgumentNullException.

2fill in blank

medium

Complete the code to catch exceptions only when the message contains 'timeout'.

C Sharp (C#)

try {
    // some code
} catch (Exception ex [1] ex.Message.Contains("timeout")) {
    Console.WriteLine("Timeout error caught.");
}

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

Awhen

Bif

Ccatch

Dfilter

Attempts:

3 left

💡 Hint

Common Mistakes

Using if instead of when in catch.

The when keyword is used to filter exceptions based on a condition.

3fill in blank

hard

Fix the error in the catch block to properly use a when clause.

C Sharp (C#)

try {
    // code
} catch (Exception ex [1] ex.Message == null) {
    Console.WriteLine("Message is null.");
}

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

Aif

Bwhere

Cwhen

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using if instead of when.

The correct keyword for filtering exceptions is when, not if or others.

4fill in blank

hard

Fill both blanks to catch InvalidOperationException only when the error code is 404.

C Sharp (C#)

try {
    // code
} catch (InvalidOperationException ex [1] ex.HResult [2] 404) {
    Console.WriteLine("Not found error caught.");
}

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

Awhen

B==

C!=

Dif

Attempts:

3 left

💡 Hint

Common Mistakes

Using if instead of when.

Using != instead of ==.

Use when to filter exceptions and == to compare the error code.

5fill in blank

hard

Fill all three blanks to catch exceptions when the message contains 'disk' and the error code is 1234.

C Sharp (C#)

try {
    // code
} catch (Exception ex [1] ex.Message.Contains("disk") && ex.HResult [2] [3]) {
    Console.WriteLine("Disk error caught.");
}

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

Awhen

B==

C1234

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using if instead of when.

Using wrong comparison operators.

The when clause filters exceptions with a condition combining message and error code checks.