native vs value struct

[dragonslayer008]

1. Can a value struct inherit from a native struct?

2. Suppose I have a native structure:

struct Vector3
{
float x, y, z;
};

and you make a corresponding managed version

value struct VectorEx3
{
float x, y, z;
};

If you have a function that takes a pointer to a Vector3 as a
parameter, is it okay to cast a VectorEx3 object to it:

VectorEx3 v;
foo( (Vector3*)&v );

I tried it and it worked, but I want to make sure it is defined
behavior.

 

[Ben Voigt [C++ MVP]]

1. Can a value struct inherit from a native struct?

No, a .NET value struct can never have a base class, only pure interfaces.

2. Suppose I have a native structure:

struct Vector3
{
float x, y, z;
};

and you make a corresponding managed version

value struct VectorEx3
{
float x, y, z;
};

If you have a function that takes a pointer to a Vector3 as a
parameter, is it okay to cast a VectorEx3 object to it:

VectorEx3 v;
foo( (Vector3*)&v );

I tried it and it worked, but I want to make sure it is defined
behavior.

It isn't guaranteed to work, and even adding the SequentialLayout attribute
only guarantees compatibility when passed through p/invoke. That said, as
long as you stick to the built-in numeric types, and structures thereof, I
don't think you'll run into any trouble.