Question

When I pass in a struct to some PInvoke method, I will receive the error

Unhandled Exception: System.AccessViolationException: Attempted to read or write
protected memory. This is often an indication that other memory is corrupt.

When I use class, then it is OK.

I want to know any reason behind that?

Answer 1

MSDN states in this article:

By default, native and managed structures are laid out differently in
memory, so successfully passing structures across the
managed/unmanaged boundary requires extra steps to preserve data
integrity.

You will also find additional information that will come in handy when using PInvoke there.