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Introduction to Programming

Code Is a Set of Instructions

At its heart, programming is just writing a list of instructions for a computer to follow. Think of it like a recipe. A recipe has ingredients (data) and steps (instructions). A computer program is the same. It tells the computer what to do with certain information, one step at a time.

Just like human languages have grammar, programming languages have rules called syntax. These rules dictate how you must write the instructions so the computer can understand them. Different languages have different syntax, but they share many of the same core ideas.

Let's look at the simplest program most people write first. It just tells the computer to display the words "Hello, World!" on the screen.

print("Hello, World!")

Here, print() is an instruction that tells the computer to show whatever is inside the parentheses. Simple, right? Every instruction in a program is a small, specific command like this.

Storing and Using Information

Games are full of information that changes: your score, your health, the number of enemies, and so on. To keep track of this information, we use variables. A variable is like a labeled box where you can store a piece of data.

variable

noun

A storage location in a computer's memory that holds a value and is identified by a name.

You can put different types of data in these boxes. Some common data types are:

  • Integers: Whole numbers, like 10, -5, or 100.
  • Strings: Text, wrapped in quotation marks, like "Hello" or "Game Over".
  • Booleans: Can only be one of two values, True or False. They are perfect for tracking things like whether a door is open or not.
# Storing the player's health
player_health = 100

# Storing the player's name
player_name = "Alex"

# Is the game over?
_is_game_over = False

Once you have data stored in variables, you can start making decisions with it. This is done with conditionals. A conditional statement checks if something is true and then runs a specific block of code. The most common one is the if statement.

Imagine your game needs to check if the player's health has reached zero.

if player_health <= 0:
  print("Game Over")

Sometimes you need to repeat an action. Maybe you need to make five enemies appear on the screen. Instead of writing the same code five times, you can use a loop. A loop repeats a block of code as long as a certain condition is met.

# This loop runs 5 times
for i in range(5):
  print("Creating an enemy!")

Organizing Code with Functions

As your programs get bigger, you'll find yourself writing the same chunks of code over and over. A function lets you package up a block of code, give it a name, and then run it whenever you want just by calling its name.

For example, think about the code for a player's jump. It might involve changing the player's position, playing a sound, and showing a jumping animation. Instead of writing all those instructions every time the player jumps, you can put them in a function called player_jump().

# Define the function
def player_jump():
  # Code for making the player jump goes here
  print("Player jumps!")

# Call the function to make it run
player_jump()

Functions make your code cleaner, easier to read, and simpler to fix if something goes wrong. If you need to change how the jump works, you only have to change it in one place: inside the player_jump function.

Blueprints for Game Objects

Games are filled with things, or objects: players, enemies, coins, bullets, and obstacles. Object-Oriented Programming (OOP) is a way of thinking about programming that's based on these real-world objects.

The first step is to create a blueprint for an object. This blueprint is called a class. A class defines what properties (data) an object has and what it can do (functions, which are called methods when they are part of a class).

A class is the blueprint. An object is the actual thing built from that blueprint.

Let's imagine a class for an enemy in a game. The blueprint might say that every enemy has health and a name. It also might define a method for taking damage.

class Enemy:
  # This runs when an object is created
  def __init__(self, name):
    self.name = name
    self.health = 50

  # A method for taking damage
  def take_damage(self, amount):
    self.health = self.health - amount
    print(self.name + " took " + str(amount) + " damage!")

# Create two actual enemy objects from the blueprint
goblin = Enemy("Goblin")
slime = Enemy("Slime")

# Use their methods
goblin.take_damage(10)
slime.take_damage(20)

In this example, goblin and slime are two separate objects, but they were both created from the same Enemy class. Each has its own name and health. This approach helps organize complex games into logical, manageable pieces.

These are the fundamental building blocks of programming. Let's review them with some flashcards before testing your knowledge.

Ready to check your understanding?

Quiz Questions 1/5

What is the fundamental role of a computer program?

Quiz Questions 2/5

If you needed to store a player's name, such as "Captain Astro", what data type would be most suitable?

Understanding these core concepts—variables, control structures, functions, and objects—is the first major step. Everything else you learn in programming will build on this foundation.