PlayerPrefs for simple data in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PlayerPrefs code?

Consider this Unity C# code snippet that uses PlayerPrefs:

PlayerPrefs.SetInt("score", 10);
PlayerPrefs.SetString("playerName", "Alex");
int score = PlayerPrefs.GetInt("score");
string name = PlayerPrefs.GetString("playerName");
Debug.Log($"Name: {name}, Score: {score}");

What will be printed in the Unity Console?

Unity

PlayerPrefs.SetInt("score", 10);
PlayerPrefs.SetString("playerName", "Alex");
int score = PlayerPrefs.GetInt("score");
string name = PlayerPrefs.GetString("playerName");
Debug.Log($"Name: {name}, Score: {score}");

A Name: Alex, Score: 10

B Name: , Score: 0

C Name: Alex, Score: 0

D Name: , Score: 10

💡 Hint

PlayerPrefs stores and retrieves data by key. The values set are returned when you get them.

The code sets "score" to 10 and "playerName" to "Alex". Then it retrieves them and prints. So the output is "Name: Alex, Score: 10".

❓ Predict Output

intermediate

What happens if a PlayerPrefs key does not exist?

Look at this code snippet:

int level = PlayerPrefs.GetInt("level");
Debug.Log(level);

Assuming "level" was never set before, what will be printed?

Unity

int level = PlayerPrefs.GetInt("level");
Debug.Log(level);

A 0

B null

C -1

D Throws an exception

💡 Hint

PlayerPrefs.GetInt returns a default value if the key is missing.

When a key does not exist, PlayerPrefs.GetInt returns 0 by default.

🔧 Debug

advanced

Why does this PlayerPrefs code not save the data?

Check this code snippet:

PlayerPrefs.SetInt("lives", 3);
// Missing PlayerPrefs.Save()
// Later in the game, trying to get the value:
int lives = PlayerPrefs.GetInt("lives");
Debug.Log(lives);

Why might the value not be saved between game sessions?

Unity

PlayerPrefs.SetInt("lives", 3);
// Missing PlayerPrefs.Save()
// Later in the game, trying to get the value:
int lives = PlayerPrefs.GetInt("lives");
Debug.Log(lives);

A Because PlayerPrefs keys must be declared before use.

B Because PlayerPrefs.SetInt only works for strings, not integers.

C Because PlayerPrefs.GetInt requires a default value parameter.

D Because PlayerPrefs.Save() was not called, changes may not be written to disk immediately.

💡 Hint

Think about when PlayerPrefs writes data to permanent storage.

PlayerPrefs.SetInt changes data in memory. To save it permanently, PlayerPrefs.Save() must be called or the application must quit normally.

📝 Syntax

advanced

Which option correctly deletes a PlayerPrefs key?

Which of the following code snippets correctly deletes the PlayerPrefs key "highscore"?

A PlayerPrefs.ClearKey("highscore");

B PlayerPrefs.Remove("highscore");

C PlayerPrefs.DeleteKey("highscore");

D PlayerPrefs.Delete("highscore");

💡 Hint

Check the exact method name for deleting a key in PlayerPrefs.

The correct method to delete a key is PlayerPrefs.DeleteKey(string key). Other options are invalid method names.

🚀 Application

expert

How many items are stored after this PlayerPrefs code runs?

Consider this sequence of PlayerPrefs commands:

PlayerPrefs.SetInt("coins", 100);
PlayerPrefs.SetString("player", "Sam");
PlayerPrefs.SetFloat("volume", 0.75f);
PlayerPrefs.DeleteKey("coins");
PlayerPrefs.SetInt("coins", 50);

How many keys are stored in PlayerPrefs after this code executes?

A 1

B 3

C 2

D 4

💡 Hint

Think about keys added, deleted, and re-added.

Initially 3 keys are set: "coins", "player", "volume". Then "coins" is deleted and set again. So total keys remain 3.