Value types vs reference types mental model in C Sharp (C#) - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a value type variable.

C Sharp (C#)

int number = [1];

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

A10

B"10"

Cnull

Dnew int()

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around numbers, which makes them strings.

Assigning null to a value type without nullable.

The variable number is a value type and can be assigned a direct integer value like 10.

2fill in blank

medium

Complete the code to declare a reference type variable.

C Sharp (C#)

string text = [1];

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

A"hello"

B10

Cnull

Dnew string()

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning numbers without quotes to string variables.

Forgetting quotes around string literals.

The variable text is a reference type and can be assigned a string literal with quotes.

3fill in blank

hard

Fix the error in copying value types.

C Sharp (C#)

int a = 5;
int b = [1];
// b should have the same value as a

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

Aref a

B&a

Ca

D*a

Attempts:

3 left

💡 Hint

Common Mistakes

Using reference operators like & or * which are not valid here.

Trying to assign by reference for value types.

Assigning b = a copies the value of a into b. Value types copy the data directly.

4fill in blank

hard

Fill both blanks to copy reference types correctly.

C Sharp (C#)

class Person { public string Name; }
Person p1 = new Person();
p1.Name = "Alice";
Person p2 = [1];
p2.Name = "Bob";
Console.WriteLine(p1.Name); // Outputs [2]

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

Ap1

B"Alice"

C"Bob"

Dnew Person()

Attempts:

3 left

💡 Hint

Common Mistakes

Creating a new object for p2 instead of copying the reference.

Expecting p1.Name to stay "Alice" after changing p2.Name.

Assigning p2 = p1 copies the reference, so both point to the same object. Changing p2.Name changes p1.Name too.

5fill in blank

hard

Fill all three blanks to create a dictionary with value types and filter by condition.

C Sharp (C#)

var scores = new Dictionary<string, int> {
    {"Alice", 90},
    {"Bob", 75},
    {"Charlie", 85}
};
var highScores = scores.Where(kv => kv.Value [1] [2]).ToDictionary(kv => kv.Key, kv => kv.Value);
Console.WriteLine(highScores[[3]]); // Outputs 90

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

A>

B80

C"Alice"

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operators.

Not quoting the dictionary key string.

Filtering with incorrect threshold.

This code filters the dictionary to include only scores greater than 80, then prints Alice's score which is 90.