Why understanding memory matters in C# - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable that stores an integer value.

C Sharp (C#)

int number = [1];

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

A"10"

B10

Ctrue

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the number, which makes it a string.

Assigning a boolean value instead of an integer.

The variable number is declared as an integer and assigned the value 10. Using quotes would make it a string, which is incorrect here.

2fill in blank

medium

Complete the code to allocate memory for a new object of class Person.

C Sharp (C#)

Person p = [1] Person();

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

Anew

Bcreate

Cmake

Dinit

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect keywords like 'create' or 'make' which are not valid in C#.

Forgetting the 'new' keyword when creating objects.

In C#, the new keyword is used to allocate memory and create a new object instance.

3fill in blank

hard

Fix the error in the code to correctly release unmanaged resources by implementing the Dispose pattern.

C Sharp (C#)

public void Dispose() [1]

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

A{ Console.WriteLine("Dispose called"); }

B{ return; }

C{ Dispose(true); GC.SuppressFinalize(this); }

D{ GC.SuppressFinalize(this); }

Attempts:

3 left

💡 Hint

Common Mistakes

Not calling the Dispose overload with the boolean parameter.

Only suppressing finalization without disposing resources.

The Dispose method should call Dispose(true) and then GC.SuppressFinalize(this) to release managed and unmanaged resources properly and prevent finalization.

4fill in blank

hard

Fill both blanks to create a dictionary that maps strings to their lengths, but only include words longer than 3 characters.

C Sharp (C#)

var lengths = new Dictionary<string, int> { { [1], [2] } };

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

A"example"

B"word"

C7

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string shorter than or equal to 3 characters.

Mismatching the string and its length.

The dictionary entry maps the string "word" to its length 4. "word" has 4 characters, which is longer than 3.

5fill in blank

hard

Fill both blanks to create a method that returns the size of an array safely, returning 0 if the array is null.

C Sharp (C#)

public int GetSize(int[] arr) { return arr [1] [2] 0; }

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

A?

B?.Length

C??

D.Length

Attempts:

3 left

💡 Hint

Common Mistakes

Not checking for null before accessing Length.

Using incorrect operators that cause errors.

The expression arr?.Length ?? 0 returns the length of the array if it is not null; otherwise, it returns 0.