How Do C Enum Classes Enhance Type Safety Compared to Plain Enums?

Type Safety in C Enum Classes

Plain enums in C have a notorious reputation for type safety issues. To enhance reliability, enum classes were introduced, boasting superior safety features.

The Difference: Scope and Conversions

Unlike plain enums, enum class enumerators are confined to the scope of their enum. Additionally, their values do not automatically convert to other types. This eliminates the possibility of implicit conversions that can lead to unintended behavior.

Example:

Consider the following code snippet:

enum class Color { red, green, blue }; // enum class
enum Animal { dog, cat, bird, human }; // plain enum

void fun() {
    Color color = Color::red;
    Animal animal = Animal::deer;

    // Triggering errors deliberately:
    int num = color; // Error: Cannot assign enum class value to int
    if (animal == Color::red) // Error: Different enum types cannot be compared
}

Benefits of Enum Classes

Enum classes prevent:

• Type conversions: Enum class values do not implicitly convert to int or other types.
• Cross-enum comparisons: Comparing enum class values from different enums is prohibited.
• Accidental conversions: Indirect conversions through other types (e.g., string to int) are also blocked.

By adhering to these rules, enum classes significantly reduce the risk of unexpected behavior stemming from mistaken enum conversions. They encourage the use of explicit casts only when necessary, enhancing code safety and maintainability.

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