Question

I am creating a geometry library in C# and I will need the following immutable types:

• Vector2f (2 floats – 8 bytes)
• Vector2d (2 doubles – 16 bytes)
• Vector3f (3 floats – 12 bytes)
• Vector3d (3 doubles – 24 bytes)
• Vector4f (4 floats – 16 bytes)
• Vector4d (4 doubles – 32 bytes)

I am trying to determine whether to make them structs or classes. MSDN suggests only using a struct if the size if going to be no greater than 16 bytes. That reference seems to be from 2005. Is 16 bytes still the max suggested size?

I am sure that using structs for the float vectors would be more efficient than using a class, but what should I do about the double vectors? Should I make them structs also to be consistent, or should I make them classes?

Updated:
Looks like the everyone agrees they should be structs. Thanks for the great answers.

Answer 1

Microsoft’s XNA Framework uses structures for its Vector2/3/4 data types. These contain fields of type float. I don’t see anything wrong with doing the same; using fields of type double shouldn’t make a big difference.