Debug.Log for debugging in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Debug.Log statement?

Consider the following Unity C# code snippet. What will be printed in the Console when this runs?

Unity

int score = 10;
Debug.Log($"Player score is: {score}");

A Error: score is not defined

B Player score is: {score}

C Player score is: 0

D Player score is: 10

💡 Hint

Look at how the $ symbol works with strings in C#.

The $ before the string allows embedding variables inside curly braces. So {score} is replaced by the value 10.

❓ Predict Output

intermediate

What does this Debug.Log print?

Look at this code snippet. What will appear in the Unity Console?

Unity

int x = 5;
int y = 3;
Debug.Log("Sum is: " + (x + y));

A Sum is: (x + y)

B Sum is: 8

C Sum is: 53

D Sum is: x + y

💡 Hint

Remember how + works with strings and numbers.

The parentheses force the addition before concatenation, so 5 + 3 = 8, then concatenated to the string.

❓ Predict Output

advanced

What error does this Debug.Log cause?

Examine this code snippet. What error will Unity show in the Console?

Unity

int[] numbers = {1, 2, 3};
Debug.Log(numbers[3]);

A IndexOutOfRangeException

B NullReferenceException

C No error, prints 3

D SyntaxError

💡 Hint

Check the array indices and their valid range.

The array has indices 0,1,2. Accessing index 3 is out of range and causes IndexOutOfRangeException.

❓ Predict Output

advanced

What will this Debug.Log print?

What is the output of this code in the Unity Console?

Unity

string playerName = null;
Debug.Log($"Player: {playerName?.ToUpper() ?? "Unknown"}");

A Player: Unknown

B Player: null

C NullReferenceException

D Player:

💡 Hint

Look at the null conditional operator and null-coalescing operator.

playerName is null, so playerName?.ToUpper() returns null, then ?? "Unknown" replaces null with "Unknown".

❓ Predict Output

expert

What is the output of this Debug.Log with a loop?

Consider this code. What will be printed in the Unity Console?

Unity

for (int i = 0; i < 3; i++)
{
    Debug.Log($"Count: {i}");
}

A

Count: 0
Count: 1
Count: 2
Count: 3

B

Count: 1
Count: 2
Count: 3

C

Count: 0
Count: 1
Count: 2

D Count: 3

💡 Hint

Remember how for loops count from start to less than end.

The loop runs with i = 0,1,2 and prints each value. It stops before i reaches 3.