What is the memory overhead of a .NET custom struct type?

Question

There is a fixed overhead associated with a .NET object as more fully outlined in this SO question: What is the memory overhead of a .NET Object being 12 or 24 bytes depending o

Answer 1

You may have some overhead with fields' alignments:

https://msdn.microsoft.com/en-us/library/system.runtime.interopservices.structlayoutattribute(v=vs.100).aspx

E.g.

  public struct Test {
    public Byte A;
    public long B;
  }

will be of size 16 bytes on 64-bit process and 12 bytes on 32-bit process correspondingly (when we could expect 9 bytes only);