VB.NET Core Classes in a Nutshell

Appendix C. Data Marshaling

When calling between the runtime environment and existing COM interfaces, the CLR performs automatic data marshaling for CLR types into compatible COM types. Table C-1 describes the Visual Basic to COM default data type mapping.

Table C-1. VB type to COM type mapping

VB type	COM type
Boolean	VARIANT_BOOL
Char	unsigned short
System.Sbyte	Char
Byte	Unsigned char
Short	Short
System.UInt16	Unsigned short
Integer	Int
System.UInt32	Unsigned int
Long	Hyper
System.UInt64	Unsigned hyper
Single	Single
Double	Double
Decimal	DECIMAL
Object	VARIANT
String	BSTR
Date	DATE [a]
System.Guid	GUID
1-dimensional arrays	SAFEARRAY
Value types	Equivalently named struct
Enum	Equivalently named enum
Interface	Equivalently named interface
Class	Equivalently named CoClass
[a] COM dates are less precise, causing comparison problems.