Marshal.SizeOf<T> Method (T)
[Supported in the .NET Framework 4.5.1 only]
Returns the unmanaged size of an object of a specified type in bytes.
Assembly: mscorlib (in mscorlib.dll)
This method accepts an instance of a structure, which can be a reference type or a boxed value type. The layout must be sequential or explicit.
The size returned is the size of the unmanaged object. The unmanaged and managed sizes of an object can differ. For character types, the size is affected by the CharSet value applied to that class.