Enums

Overview

Enums assign readable names to integer constants, making code much more legible. `enum class` (C++11) provides strongly-typed, scoped enums.

Syntax

cpp

// Old C-style Enum
enum Color { RED, GREEN, BLUE }; // RED=0, GREEN=1...
Color c = RED;

// Modern C++ Scoped Enum (enum class)
enum class Status { PENDING, APPROVED, REJECTED };
Status s = Status::APPROVED;

Common Pitfalls

Trying to print an `enum class` directly to `cout`. It won't implicitly cast to an int; you must cast it explicitly: `static_cast<int>(Status::APPROVED)`.

Interview Tips

Explain why `enum class` is preferred: Old enums export their variables to the global scope (so you can't have a `RED` in two different enums), and they implicitly convert to integers. `enum class` is scoped and strongly typed.

Real-World Example

Using switch statements with strongly-typed enums.

example

cpp

#include <iostream>
using namespace std;

enum class TrafficLight { RED, YELLOW, GREEN };

int main() {
    TrafficLight light = TrafficLight::GREEN;
    
    switch (light) {
        case TrafficLight::RED: cout << "Stop\n"; break;
        case TrafficLight::YELLOW: cout << "Slow down\n"; break;
        case TrafficLight::GREEN: cout << "Go\n"; break;
    }
    return 0;
}

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