Understanding Variables and Data Types

Variables: The Storage Boxes of Programming

Variables are like labeled boxes where we store information that our programs can use and modify. Understanding variables is fundamental to all programming.

What is a Variable?

A variable is a named storage location that holds data. Think of it as a box with a label on it. You can put things in the box, take them out, or replace them with something else.

// Creating a variable named "age" and storing the value 25
    age = 25
    
    // Creating a variable named "name" and storing text
    name = "Alice"
    
    // Using variables
    print("Hello, " + name + "! You are " + age + " years old.")

Common Data Types

1. Numbers

• Integers: Whole numbers like 1, 42, -17
• Decimals: Numbers with decimal points like 3.14, -0.5

2. Text (Strings)

Text data enclosed in quotes: "Hello World", "Programming is fun!"

3. Boolean (True/False)

Values that are either true or false: true, false

4. Lists/Arrays

Collections of items: [1, 2, 3, 4] or ["apple", "banana", "orange"]

// Numbers
    score = 100
    temperature = 98.6
    
    // Text/String
    message = "Welcome to programming!"
    
    // Boolean
    isLoggedIn = true
    gameOver = false
    
    // List
    colors = ["red", "green", "blue"]
    numbers = [1, 2, 3, 4, 5]

Variable Naming Rules

• Use descriptive names: userName instead of x
• Start with a letter, not a number
• No spaces (use camelCase or underscores): firstName or first_name
• Avoid special characters except underscore

Why Data Types Matter

Different data types can do different things:

• Numbers can be added, subtracted, multiplied
• Strings can be combined or searched
• Booleans help make decisions in programs
• Lists can store multiple related items

Common Mistakes to Avoid

• Forgetting quotes around text: name = Alice ❌ vs name = "Alice" ✅
• Using reserved words as variable names
• Inconsistent naming conventions