What are enumerations and how to use them in C++

In C++, an enumeration (or enum) is a way to define a set of named integer values under a single type.

Each member of an enumeration is a constant that represents a unique integer value (starting at 0 by default and increasing by one for each subsequent member).

Defining an Enumeration

To define an enumeration in C++, use the keyword enum, followed by the enumeration name and its members within braces.

enum DiasDeLaSemana
{
    Lunes,
    Martes,
    Miércoles,
    Jueves,
    Viernes,
    Sábado,
    Domingo
};

Enumerations with specific values

It is possible to assign specific values to enumeration members (instead of using the default values).

enum DiasSemana
{
    Lunes = 1,
    Martes = 2,
    Miércoles = 3,
    Jueves = 4,
    Viernes = 5,
    Sábado = 6,
    Domingo = 7
};

If the numbers are sequential, you can number only the first one (the rest will be assigned automatically in sequential order).

enum DiasSemana
{
    Lunes = 1,
    Martes,
    Miércoles,
    Jueves,
    Viernes,
    Sábado,
    Domingo
};

Using Enumerations

DiasDeLaSemana hoy = Lunes;

if (hoy == Lunes)
{
    std::cout << "Today is Monday." << std::endl;
}

Enumeration Conversion

Enumerations in C++ are based on integer data types. Therefore, it is possible to convert between an enumeration and its underlying type (which by default is int).

int valorNumerico = static_cast<int>(Miércoles);
std::cout << valorNumerico << std::endl; // Output: 2

DiasDeLaSemana dia = static_cast<DiasDeLaSemana>(4);
std::cout << dia << std::endl; // Output: 4 (depending on the implementation, it may require an additional cast to print the name)

Scoped Enumerations

Scoped enumerations (enum class or enum struct) are a safer way to define enumerations in C++, as the values of a scoped enumeration do not implicitly convert to integers and do not enter the global scope.

The syntax to create a scoped enumeration:

enum class NombreEnum : tipo_base {
    Valor1,
    Valor2,
    // More values
};

For example,

enum class Color : char {
    Rojo,
    Verde,
    Azul
};

Color c = Color::Rojo;

Practical Examples

enum EstadoTarea
{
    Pendiente,
    EnProgreso,
    Completada,
    Cancelada
};

class Tarea
{
public:
    std::string Nombre;
    EstadoTarea Estado;

    void mostrarEstado()
    {
        std::cout << "The task '" << Nombre << "' is in state: " << Estado << std::endl;
    }
};

int main()
{
    Tarea tarea;
    tarea.Nombre = "Study for the exam";
    tarea.Estado = EnProgreso;

    tarea.mostrarEstado(); // Output: The task 'Study for the exam' is in state: 1
    return 0;
}

enum TipoDeEnemigo
{
    Goblin,
    Orco,
    Dragon
};

class Enemigo
{
public:
    TipoDeEnemigo Tipo;

    void mostrarTipo()
    {
        std::cout << "This enemy is a: " << Tipo << std::endl;
    }
};

int main()
{
    Enemigo enemigo;
    enemigo.Tipo = Dragon;

    enemigo.mostrarTipo(); // Output: This enemy is a: 2
    return 0;
}