Common bugs from reference sharing in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new list that does not share the reference with the original list.

C Sharp (C#)

List<int> original = new List<int> {1, 2, 3};
List<int> copy = original[1];
copy.Add(4);
Console.WriteLine(original.Count);

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

A.ToList()

B.Add()

C.Clear()

D.RemoveAt(0)

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods that modify the original list instead of copying it.

Using .ToList() creates a new list copy, so changes to copy don't affect original.

2fill in blank

medium

Complete the code to avoid modifying the original array when changing the copy.

C Sharp (C#)

int[] original = {1, 2, 3};
int[] copy = (int[])original[1];
copy[0] = 10;
Console.WriteLine(original[0]);

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AClone()

BCopyTo()

CResize()

DClear()

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods that only copy references or clear the array.

Clone() creates a shallow copy of the array, so modifying copy does not affect original.

3fill in blank

hard

Fix the error in the code to prevent shared reference issues with objects.

C Sharp (C#)

class Person {
    public string Name;
}

Person p1 = new Person { Name = "Alice" };
Person p2 = p1;
p2.Name = "Bob";
Console.WriteLine([1].Name);

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Anull

Bp2

Cnew Person()

Dp1

Attempts:

3 left

💡 Hint

Common Mistakes

Assuming p1 and p2 are independent objects after assignment.

Both p1 and p2 reference the same object, so changing p2.Name also changes p1.Name.

4fill in blank

hard

Fill both blanks to create a deep copy of a list of objects to avoid shared references.

C Sharp (C#)

List<Person> original = new List<Person> { new Person { Name = "Anna" } };
List<Person> copy = original.Select(p => new Person [1]).ToList();
copy[0].Name = [2];
Console.WriteLine(original[0].Name);

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A{ Name = p.Name }

B"Elsa"

C"Anna"

D{ Name = "Elsa" }

Attempts:

3 left

💡 Hint

Common Mistakes

Copying the list without copying the objects inside.

Using Select with a new Person copies each object, avoiding shared references. Changing copy[0].Name does not affect original[0].Name.

5fill in blank

hard

Fill all three blanks to correctly clone a dictionary and modify the copy without affecting the original.

C Sharp (C#)

Dictionary<string, int> original = new Dictionary<string, int> { {"a", 1}, {"b", 2} };
Dictionary<string, int> copy = original.ToDictionary([1], [2]);
copy["a"] = [3];
Console.WriteLine(original["a"]);

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Apair => pair.Key

Bpair => pair.Value

C10

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Modifying the original dictionary by mistake due to shared references.

ToDictionary creates a new dictionary by copying keys and values. Changing copy["a"] does not affect original["a"].