C# Struct usage tips?

Question

I like using structs a lot.

So after reading this article, are there any other concerns I should have against using them all the time?

See Also:

• When should I use a struct instead of a class?
• When to use struct in C#?

Answer 1

You should make the following considerations about structs:

• structs should be immutable (mutable structs are not intuitive and unpredictable)
• structs always have a default (public parameterless) constructor that cannot be changed
• struct size should not exceed 16 bytes
• the Equals and GetHashCode methods should be overriden for better performance
• implementing the IEquatable<T> interface is recommended
• redefining and == and the != operators is also recommended

Answer 2

I almost never define custom structs. There just aren't that many natural value types around, IMO.

In particular, I would think very, very carefully before defining a mutable struct, especially if it mutates via an interface implementation. Mutable structs behave in ways which people don't expect at all, leading to code which is hard to understand.

I think it's worth reading "Choosing Between Classes and Structures" from "Design Guidelines For Developing Class Libraries".

In particular:

Do not define a structure unless the type has all of the following characteristics:

• It logically represents a single value, similar to primitive types (integer, double, and so on).

• It has an instance size smaller than 16 bytes.

• It is immutable.

• It will not have to be boxed frequently.

Do you really develop types with all of those characteristics frequently?

Answer 3

They don't fit into an Object Oriented programming paradigm like classes do. They are good for small data structures, but I use classes for anything beyond that.