First Unity project (Hello World scene) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Unity C# script?

Consider this simple Unity script attached to a GameObject. What will be printed in the Console when you run the scene?

Unity

using UnityEngine;

public class HelloWorld : MonoBehaviour
{
    void Start()
    {
        Debug.Log("Hello, Unity World!");
    }
}

A Hello, Unity World!

B Error: Debug.Log is undefined

C Nothing is printed

D Hello World

💡 Hint

Look at what Debug.Log prints inside the Start method.

The Start method runs once when the scene starts. Debug.Log prints the exact string to the Console, so it prints "Hello, Unity World!".

🧠 Conceptual

intermediate

Which Unity method runs exactly once when the scene starts?

In Unity scripts, which method is called automatically once when the scene begins?

A FixedUpdate()

B Update()

C Start()

D Awake()

💡 Hint

Think about the method that runs after all Awake methods but before the first frame.

Start() is called once before the first frame update. Awake() runs earlier but also once. However, Start() is the common method to initialize things when the scene starts.

🔧 Debug

advanced

Why does this script not print anything in the Console?

Look at this script attached to a GameObject. Why does it not print "Hello World" when the scene runs?

Unity

using UnityEngine;

public class HelloWorld : MonoBehaviour
{
    void start()
    {
        Debug.Log("Hello World");
    }
}

A The method name should be capitalized as Start() to be called by Unity.

B Debug.Log cannot print strings, only numbers.

C The script must inherit from ScriptableObject, not MonoBehaviour.

D The GameObject is inactive, so scripts never run.

💡 Hint

Unity calls specific methods by exact names and capitalization.

Unity calls the Start() method with capital S automatically. The method named start() with lowercase s is ignored, so nothing prints.

📝 Syntax

advanced

Which option fixes the syntax error in this Unity C# script?

This script has a syntax error. Choose the option that fixes it so it compiles and prints "Hello World".

Unity

using UnityEngine;

public class HelloWorld : MonoBehaviour
{
    void Start()
    {
        Debug.Log("Hello World"
    }
}

A Remove the semicolon after Debug.Log("Hello World")

B Change Debug.Log to Debug.Print("Hello World");

C Add a return type int to Start method: int Start()

D Add a closing parenthesis after the string: Debug.Log("Hello World");

💡 Hint

Check if all parentheses and semicolons are correctly placed.

The Debug.Log call is missing a closing parenthesis and semicolon. Adding them fixes the syntax error.

🚀 Application

expert

How many GameObjects are created after running this script?

This script creates new GameObjects in the scene. How many GameObjects exist after Start() finishes?

Unity

using UnityEngine;

public class CreateObjects : MonoBehaviour
{
    void Start()
    {
        for (int i = 0; i < 3; i++)
        {
            GameObject obj = new GameObject($"Object_{i}");
        }
    }
}

A 3 GameObjects named Object_0, Object_1, Object_2

B 4 GameObjects including the one with this script attached

C 1 GameObject named Object_2 because previous are overwritten

D 0 GameObjects because new GameObject() does not add to scene

💡 Hint

Remember the original GameObject with this script plus the new ones created.

The script creates 3 new GameObjects plus the original GameObject that has this script attached, so total 4 GameObjects exist.