Variant Type Definitions

COM Data Types

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Variant Type Definitions

One of the most irritating problems when debugging COM code is trying to decide what the VARTYPE vt of a Variant structure actually means. This page lists the translations between the numbers and the types and describes what the types mean.

**Numerical Definitions of Variant Types**
Variant Type	Num	Variant Type	Num	Variant Type	Num
VT_EMPTY	0	VT_NULL	1	VT_I2	2
VT_I4	3	VT_R4	4	VT_R8	5
VT_CY	6	VT_DATE	7	VT_BSTR	8
VT_DISPATCH	9	VT_ERROR	10	VT_BOOL	11
VT_VARIANT	12	VT_UNKNOWN	13	VT_DECIMAL	14
VT_I1	16	VT_UI1	17	VT_UI2	18
VT_UI4	19	VT_I8	20	VT_UI8	21
VT_INT	22	VT_UINT	23	VT_VOID	24
VT_HRESULT	25	VT_PTR	26	VT_SAFEARRAY	27
VT_CARRAY	28	VT_USERDEFINED	29	VT_LPSTR	30
VT_LPWSTR	31	VT_FILETIME	64	VT_BLOB	65
VT_STREAM	66	VT_STORAGE	67	VT_STREAMED_OBJECT	68
VT_STORED_OBJECT	69	VT_BLOB_OBJECT	70	VT_CF	71
VT_CLSID	72	VT_VECTOR	0x1000	VT_ARRAY	0x2000
VT_BYREF	0x4000	VT_RESERVED	0x8000	VT_ILLEGAL	0xffff
VT_ILLEGALMASKED	0xfff	VT_TYPEMASK	0xfff

Usage and Descriptions of Variant Types

Key:

[V] - may appear in a VARIANT

[T] - may appear in a TYPEDESC

[P] - may appear in an OLE property set

[S] - may appear in a Safe Array

Variant Type	Usage	Description
VT_EMPTY	[V] [P]	nothing
VT_NULL	[V] [P]	SQL style Null
VT_I2	[V][T][P][S]	2 byte signed int
VT_I4	[V][T][P][S]	4 byte signed int
VT_R4	[V][T][P][S]	4 byte real
VT_R8	[V][T][P][S]	8 byte real
VT_CY	[V][T][P][S]	currency
VT_DATE	[V][T][P][S]	date
VT_BSTR	[V][T][P][S]	OLE Automation string
VT_DISPATCH	[V][T][P][S]	IDispatch *
VT_ERROR	[V][T] [S]	SCODE
VT_BOOL	[V][T][P][S]	True=-1, False=0
VT_VARIANT	[V][T][P][S]	VARIANT *
VT_UNKNOWN	[V][T] [S]	IUnknown *
VT_DECIMAL	[V][T] [S]	16 byte fixed point
VT_I1	[T]	signed char
VT_UI1	[V][T][P][S]	unsigned char
VT_UI2	[T][P]	unsigned short
VT_UI4	[T][P]	unsigned short
VT_I8	[T][P]	signed 64-bit int
VT_UI8	[T][P]	unsigned 64-bit int
VT_INT	[T]	signed machine int
VT_UINT	[T]	unsigned machine int
VT_VOID	[T]	C style void
VT_HRESULT	[T]	Standard return type
VT_PTR	[T]	pointer type
VT_SAFEARRAY	[T]	(use VT_ARRAY in VARIANT)
VT_CARRAY	[T]	C style array
VT_USERDEFINED	[T]	user defined type
VT_LPSTR	[T][P]	null terminated string
VT_LPWSTR	[T][P]	wide null terminated string
VT_FILETIME	[P]	FILETIME
VT_BLOB	[P]	Length prefixed bytes
VT_STREAM	[P]	Name of the stream follows
VT_STORAGE	[P]	Name of the storage follows
VT_STREAMED_OBJECT	[P]	Stream contains an object
VT_STORED_OBJECT	[P]	Storage contains an object
VT_BLOB_OBJECT	[P]	Blob contains an object
VT_CF	[P]	Clipboard format
VT_CLSID	[P]	A Class ID
VT_VECTOR	[P]	simple counted array
VT_ARRAY	[V]	SAFEARRAY*
VT_BYREF	[V]	void* for local use