Enumerations | Data Types | Cplusplus Tutorial

Introduction

Enumerations (enums) are a user-defined data type in C++ that consist of integral constants. To define an enumeration, the enum keyword is used. Enums are used to assign names to the integral constants which make a program easy to read and maintain.

Defining an Enumeration

To define an enumeration, you use the enum keyword followed by the name of the enumeration and the list of constants enclosed in curly braces.

enum Color {RED, GREEN, BLUE};

In this example, Color is an enumeration with three constants: RED, GREEN, and BLUE. By default, the value of RED is 0, GREEN is 1, and BLUE is 2.

Using Enumerations

You can declare variables of the type of an enumeration and assign one of the enum constants to them.

Color myColor;
myColor = RED;

Here, myColor is a variable of type Color and is assigned the value RED.

Enumerations with Specific Values

You can also assign specific values to the constants in an enumeration.

enum Fruit {APPLE = 2, ORANGE = 4, BANANA = 6};

In this example, APPLE has the value 2, ORANGE has the value 4, and BANANA has the value 6.

Enumeration Scope

By default, enumerations have global scope. However, you can use the enum class (or enum struct) keyword to define scoped enumerations which help avoid name conflicts.

enum class Color {RED, GREEN, BLUE};
enum class Fruit {APPLE, ORANGE, BANANA};

In this example, Color and Fruit are scoped enumerations. To use the constants, you need to specify the enumeration name.

Color myColor = Color::RED;
Fruit myFruit = Fruit::APPLE;

Advantages of Enumerations

Enumerations provide several advantages:

Improved code readability
Better error checking
Namespace management with scoped enums

Example Program

Here is a complete example program that demonstrates the usage of enumerations in C++:

#include <iostream>
using namespace std;

enum class Color {RED, GREEN, BLUE};
enum class Fruit {APPLE, ORANGE, BANANA};

int main() {
    Color myColor = Color::GREEN;
    Fruit myFruit = Fruit::BANANA;

    if (myColor == Color::GREEN) {
        cout << "The color is green." << endl;
    }

    if (myFruit == Fruit::BANANA) {
        cout << "The fruit is banana." << endl;
    }

    return 0;
}

In this program, we define two scoped enumerations: Color and Fruit. We then use these enums to set the values and compare them in if statements.

Enumerations in C++