Enumerations

🎨 The Label Maker’s Magic: C++ Enumerations

🌟 Once Upon a Time in Label Land…

Imagine you have a magical label maker. Instead of remembering numbers like “1 means Red, 2 means Blue, 3 means Green,” you just write the actual words!

That’s exactly what enumerations do in C++. They let you create named labels so your code is easy to read and understand.

📦 Chapter 1: Plain Enumerations (The Classic Labels)

What Are They?

Think of a plain enum like a crayon box where each crayon has a name AND a hidden number.

enum Color {
    Red,    // secretly = 0
    Green,  // secretly = 1
    Blue    // secretly = 2
};

How to Use Them

Color myFavorite = Red;

if (myFavorite == Red) {
    // Do something red!
}

🎯 The Hidden Numbers

Each label gets a number automatically, starting from 0:

enum Day {
    Monday,    // 0
    Tuesday,   // 1
    Wednesday  // 2
};

You can also pick your own numbers:

enum Level {
    Easy = 1,
    Medium = 5,
    Hard = 10
};

⚠️ The Problem with Plain Enums

Plain enums are a bit messy. They spill their names everywhere!

enum Fruit { Apple, Orange };
enum Tech { Apple, Windows };
// ERROR! Two "Apple" names clash!

This is like having two kids named “Alex” in the same classroom. Confusing!

🏰 Chapter 2: Enum Classes (The Safe Labels)

The Super-Safe Solution

C++11 introduced enum class — think of it as putting each label set in its own labeled box.

enum class Fruit { Apple, Orange };
enum class Tech { Apple, Windows };
// No problem! Each Apple is in its own box!

How to Use Enum Classes

You must say which box the label comes from:

Fruit mySnack = Fruit::Apple;
Tech myDevice = Tech::Apple;

// Clear and safe!
if (mySnack == Fruit::Apple) {
    // Yummy!
}

🔒 Why Enum Classes Are Better

Converting to Numbers (When You Need To)

enum class Size { Small, Medium, Large };

Size shirt = Size::Medium;

// Need the number? Ask explicitly:
int num = static_cast<int>(shirt);
// num is now 1

🪄 Chapter 3: Using Enum (The Shortcut Spell)

The Magic Words: using enum

Tired of typing the box name every time? C++20 gives you a shortcut!

enum class Direction {
    Up, Down, Left, Right
};

void move() {
    using enum Direction;

    // Now you can just say:
    Direction d = Up;  // No need for Direction::Up

    if (d == Left) {
        // Turn left!
    }
}

🎮 Real Example: Game Controls

enum class Button {
    A, B, X, Y, Start, Select
};

void handleInput(Button pressed) {
    using enum Button;

    switch (pressed) {
        case A:     jump();    break;
        case B:     attack();  break;
        case X:     defend();  break;
        case Y:     special(); break;
        case Start: pause();   break;
        case Select: menu();   break;
    }
}

⚠️ Use With Care!

using enum brings all names into your current scope. Use it inside functions to keep things tidy.

🗺️ The Complete Picture

graph TD
    A["Enumerations"] --> B["Plain enum"]
    A --> C["enum class"]
    A --> D["using enum"]

    B --> B1["Names visible everywhere"]
    B --> B2["Can clash with other names"]
    B --> B3["Auto-converts to int"]

    C --> C1["Names in their own scope"]
    C --> C2["No name clashes"]
    C --> C3["Must use ScopeName::Value"]

    D --> D1["C++20 shortcut"]
    D --> D2["Brings names into scope"]
    D --> D3["Use inside functions"]

💡 Quick Tips

When to Use What?

🎨 Set Your Own Type

Both can specify their underlying number type:

enum class SmallSize : uint8_t {
    Tiny,
    Small,
    Medium
};
// Uses only 1 byte!

🎉 You Did It!

You now know:

1. ✅ Plain enums — Simple labels with hidden numbers
2. ✅ Enum classes — Safe labels in their own boxes
3. ✅ Using enum — The shortcut to avoid typing

Enumerations make your code readable, safe, and meaningful. No more mysterious numbers!

🧙‍♂️ Pro Wisdom: Always prefer enum class in modern C++. It’s like wearing a seatbelt — a small habit that prevents big problems!