Summary  
This chapter explains how to declare and name functions, define their parameters and body, handle optional return values, and invoke them with objects to perform actions.  

General domain of usage  
Game development (character behavior control)


### Parts of a Function

- **Declaration**: It starts with the `function` keyword.
- **Name**: The identifier for the function like `ninjaController`, `lootBox`, etc.
- **Parameters**: Variables listed in parentheses that accept values when the function is called.
- **Body**: A block of code inside curly braces `{}` which performs the function's actions.
- **Return Value**: Optional statement to output a value. Without it, functions return `undefined`.

### Example


ZGVmIG5pbmphX2NvbnRyb2xsZXIobmluamEpOgoJbG9vdF9ib3gobmluamEpCgluaW5qYS5nb19yaWdodCgpCgluaW5qYS5nb19yaWdodCgpCgluaW5qYS5nb19yaWdodCgpCgluaW5qYS5nb19yaWdodCgpCglsb290X2JveChuaW5qYSkKCmRlZiBsb290X2JveChuaW5qYSk6CgluaW5qYS5nb191cCgpCgluaW5qYS5waWNrX3N1c2hpKCkKCW5pbmphLmdvX2Rvd24oKQoJbmluamEuZ29fZG93bigpCgluaW5qYS5waWNrX3N1c2hpKCkKCW5pbmphLmdvX3VwKCkK

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

Z2FtZV9tYXAgPSBbWzAsMCwwLDAsMCwwLDAsMCwwXSxbMCwwLDAsMCwwLDAsMCwwLDBdLFswLDEsMSwxLDAsMSwxLDEsMF0sWzAsMSwzLDEsMCwxLDMsMSwwXSxbMCwxLDIsMCwwLDAsMCwxLDBdLFswLDEsMywxLDAsMSwzLDEsMF0sWzAsMSwxLDEsMCwxLDEsMSwwXSxbMCwwLDAsMCwwLDAsMCwwLDBdLFswLDAsMCwwLDAsMCwwLDAsMF1dOwo=


- `ninjaController` : Controls the ninja by calling `lootBox` twice and moving right four times.

- `lootBox` : Defines a set of actions (moving, picking sushi) for the ninja.

- Parameter: Both functions take a ninja object that has methods like `goRight()` , `goUp()` , etc.

Welcome to the Python Ninja Course! This engaging and interactive course is designed to introduce you to the fundamentals of Python programming through a fun and educational game. You'll guide a ninja through various challenges, using Python to control movements and interact with objects like sushi. Starting with the basics, you'll learn how to navigate the map, pick up and place sushi, and gradually progress to more complex programming concepts such as functions, loops, and conditional statements. Each chapter offers hands-on practice to reinforce your learning, culminating in exciting challenges that test your skills. Whether you're a complete beginner or looking to sharpen your coding abilities, this course provides a comprehensive and enjoyable learning experience. Join us and become a coding ninja!

In the "Basic Controls" section, you'll be introduced to the foundational features of Python through the engaging Ninja Game. You'll learn how to use Python commands to control your ninja's movements and interactions on the grid, mastering essential functions like moving, picking up, and placing sushi. Through hands-on practice, you'll apply these skills to solve fun challenges, reinforcing your understanding of Python's basic capabilities.

In the "Functions" section, you'll delve into the powerful Python feature of creating and utilizing functions to streamline your code. You'll learn how to write functions to perform specific tasks, enhancing code reusability and clarity. By practicing decomposition, you'll break down complex problems into simpler functions, mastering the art of organized and efficient coding.

In the "Loops" section, you'll explore the essential Python feature of loops, which allows you to execute repetitive tasks efficiently. You'll learn to implement both for loops and while loops, gaining the ability to automate actions and iterate over sequences. By mastering nested loops, you'll tackle more complex scenarios, enhancing your ability to write concise and powerful code.

In the "If-Else Statements" section, you'll learn how to use Python's conditional logic to make decisions within your code. You'll explore how if-else statements allow your ninja to respond dynamically to different scenarios, enabling more intelligent and adaptable behavior. Through practical exercises, you'll apply these concepts to solve challenges, enhancing your ability to write responsive and decision-driven code.

In the "Challenges" section, you'll apply your Python skills to tackle a series of engaging and complex problems. These challenges will test your understanding of loops, functions, and conditional logic as you guide your ninja to align columns, build letters, and traverse intricate patterns. By solving these puzzles, you'll refine your coding abilities and gain confidence in applying Python to creative and real-world scenarios.

Writing Functions

Parts of a Function

Example

Løsning