Why Does C# Allow Non-Unique Enum Values, and Should I Use a Struct Instead?

Non-Unique Enum Values

Question:

In C#, why does the compiler allow multiple enums to be assigned to the same value? Is it advisable to use a struct instead in such cases?

Answer:

An enum in C# is essentially a struct that inherits from the System.Enum base class. Behind the scenes, the enum values are defined as constants within the struct. For example, the following enum definition:

public enum Color
{
    Red = 1,
    Blue = 1,
    Green = 1
}

Is equivalent to the following pseudo C# code:

public struct Color : System.Enum
{
    public const int Red = 1;
    public const int Blue = 1;
    public const int Green = 1;
}

Since there is no issue with a type containing multiple constants with the same value, defining enums with non-unique values is permissible. However, it comes with some caveats:

1. Non-unique Values: When converting to an enum with non-unique values, the first value assigned to the enum will be the one returned. This may not align with the intended value.
2. Equality Comparisons: Comparing non-unique enum values may result in unexpected results. Using the example in the question, both Red and Green represent the value 1, so comparing Red to Green will return true despite their inherent difference.

While it is technically legal to use non-unique enum values, it generally discouraged. Instead, consider using a struct, which allows you to define explicit members with unique values. However, structs may have a higher memory overhead compared to enums, so use them judiciously based on your requirements.

The above is the detailed content of Why Does C# Allow Non-Unique Enum Values, and Should I Use a Struct Instead?. For more information, please follow other related articles on the PHP Chinese website!