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4/8/2010

The VARIANT and VARIANTARG structure is used to describe arguments passed within DISPPARAMSstructures.

Syntax 

struct tagVARIANT
  {
  union 
	{
	struct __tagVARIANT
	{
	VARTYPE 
vt;
	WORD 
wReserved1;
	WORD 
wReserved2;
	WORD 
wReserved3;
	union 
		{
		LONG 
lVal;
		BYTE 
bVal;
		SHORT 
iVal;
		FLOAT 
fltVal;
		DOUBLE 
dblVal;
		VARIANT_BOOL 
boolVal;

		_VARIANT_BOOL 
bool;
		SCODE 
scode;
		CY 
cyVal;
		DATE 
date;
		BSTR 
bstrVal;
		IUnknown __RPC_FAR* 
punkVal;
		IDispatch __RPC_FAR* 
pdispVal;
		SAFEARRAY __RPC_FAR* 
parray;
		BYTE __RPC_FAR*
 pbVal;
		SHORT __RPC_FAR*
 piVal;
		LONG __RPC_FAR* 
plVal;
		FLOAT __RPC_FAR* 
pfltVal;
		DOUBLE __RPC_FAR* 
pdblVal;
		VARIANT_BOOL __RPC_FAR*
 pboolVal;
		_VARIANT_BOOL __RPC_FAR* 
pbool;
		SCODE __RPC_FAR* 
pscode;
		CY __RPC_FAR* 
pcyVal;
		DATE __RPC_FAR* 
pdate;
		BSTR __RPC_FAR* 
pbstrVal;
		IUnknown __RPC_FAR*__RPC_FAR * 
ppunkVal;
		IDispatch __RPC_FAR*__RPC_FAR * 
ppdispVal;
		SAFEARRAY __RPC_FAR*__RPC_FAR * 
pparray;
		VARIANT __RPC_FAR* 
pvarVal;
		PVOID 
byref;
		CHAR 
cVal;
		USHORT 
uiVal;
		ULONG 
ulVal;
		INT intVal;
		UINT 
uintVal;
		DECIMAL __RPC_FAR* 
pdecVal;
		CHAR __RPC_FAR* 
pcVal;
		USHORT __RPC_FAR* 
puiVal;
		ULONG __RPC_FAR* 
pulVal;
		INT __RPC_FAR* 
pintVal;
		UINT __RPC_FAR* 
puintVal;
		struct __tagBRECORD
		{
		PVOID 
pvRecord;
		IRecordInfo __RPC_FAR* 
pRecInfo;
	}   __VARIANT_NAME_4;
	}   __VARIANT_NAME_3;
}   __VARIANT_NAME_2;

	DECIMAL 
decVal;
}   __VARIANT_NAME_1;
  };
typedef /* [wire_marshal] */ struct tagVARIANT VARIANT;
typedef VARIANT __RPC_FAR *LPVARIANT;
typedef VARIANT VARIANTARG;
typedef VARIANT __RPC_FAR *LPVARIANTARG;

Members

vt

Contains the type code for the variant, which governs how the variant is interpreted. For more information, see Remarks.

wReserved1

Reserved. Pads the structure so the variant data begins on an eight-byte boundary.

wReserved2

Reserved. Pads the structure so the variant data begins on an eight-byte boundary.

wReserved3

Reserved. Pads the structure so the variant data begins on an eight-byte boundary.

lVal

VT_I4. For more information, see Remarks.

bVal

VT_UI1. For more information, see Remarks.

iVal

VT_I2. For more information, see Remarks.

fltVal

VT_R4. For more information, see Remarks.

dblVal

VT_R8. For more information, see Remarks.

boolVal

VT_BOOL. For more information, see Remarks.

bool

For more information, see Remarks.

scode

VT_ERROR. For more information, see Remarks.

cyVal

VT_CY. For more information, see Remarks.

date

VT_DATE. For more information, see Remarks.

bstrVal

VT_BSTR. For more information, see Remarks.

punkVal

VT_UNKNOWN. For more information, see Remarks.

pdispVal

VT_DISPATCH. For more information, see Remarks.

parray

VT_ARRAY | *. For more information, see Remarks.

pbVal

VT_BYREF | VT_UI1. For more information, see Remarks.

piVal

VT_BYREF | VT_I2. For more information, see Remarks.

plVal

VT_BYREF | VT_I4. For more information, see Remarks.

pfltVal

VT_BYREF | VT_R4. For more information, see Remarks.

pdblVal

VT_BYREF | VT_R8. For more information, see Remarks.

pboolVal

VT_BYREF | VT_BOOL. For more information, see Remarks.

pbool

For more information, see Remarks.

pscode

VT_BYREF | VT_ERROR. For more information, see Remarks.

pcyVal

VT_BYREF | VT_CY. For more information, see Remarks.

pdate

VT_BYREF | VT_DATE. For more information, see Remarks.

pbstrVal

VT_BYREF | VT_BSTR. For more information, see Remarks.

ppunkVal

VT_BYREF | VT_UNKNOWN. For more information, see Remarks.

ppdispVal

VT_BYREF | VT_DISPATCH. For more information, see Remarks.

pparray

VT_ARRAY | *. For more information, see Remarks.

pvarVal

VT_BYREF | VT_VARIANT. For more information, see Remarks.

byref

Generic reference pointer.

cVal

VT_I1. For more information, see Remarks.

uiVal

VT_UI2. For more information, see Remarks.

ulVal

VT_UI4. For more information, see Remarks.

intVal

VT_INT. For more information, see Remarks.

uintVal

VT_UINT. For more information, see Remarks.

pdecVal

VT_DECIMAL | VT_BYREF. For more information, see Remarks.

pcVal

VT_I1 | VT_BYREF. For more information, see Remarks.

puiVal

VT_UI2 | VT_BYREF. For more information, see Remarks.

pulVal

VT_UI4 | VT_BYREF. For more information, see Remarks.

pintVal

VT_INT | VT_BYREF. For more information, see Remarks.

puintVal

VT_UINT | VT_BYREF. For more information, see Remarks.

pvRecord

For more information, see Remarks.

pRecInfo

For more information, see Remarks.

decVal

For more information, see Remarks.

Remarks

To simplify extracting values from VARIANTARGs, Automation provides a set of functions for manipulating this type. Use of these functions is strongly recommended to ensure that applications apply consistent coercion rules.

The VARIANTtype cannot have the VT_BYREFbit set.

The vtvalue governs the interpretation of the union. The following table shows the possible values for vt.

Value Description

VT_ARRAY | <anything>

An array of data type <anything> was passed. VT_EMPTY and VT_NULL are invalid types to combine with VT_ARRAY. The pointer in pbyrefValpoints to an array descriptor, which describes the dimensions, size, and in-memory location of the array.

VT_BOOL

A Boolean, True/False, value was specified. A value of 0xFFFF, all bits set to one, indicates True; a value of 0x0000, all bits set to zero, indicates False. No other values are valid.

VT_BOOL | VT_BYREF

A reference to a Boolean value. A pointer to the Boolean value is in pbool.

VT_BSTR

A string was passed; it is stored in bstrVal. This pointer must be obtained and freed by the BSTR functions.

VT_BSTR | VT_BYREF

A reference to a string was passed. A BSTR* that points to a BSTR is in pbstrVal. The referenced pointer must be obtained or freed by the BSTR functions.

VT_CY

A currency value was specified. A currency number is stored as an 8-byte, two's complement integer, scaled by 10,000 to give a fixed-point number with 15 digits to the left of the decimal point and 4 digits to the right. The value is in cyVal.

VT_CY | VT_BYREF

A reference to a currency value was passed. A pointer to the value is in pcyVal.

VT_DATE

A value denoting a date and time was specified. Dates are represented as double-precision numbers, where midnight, January 1, 1900 is 2.0, January 2, 1900 is 3.0, and so on. The value is passed in date.

This is the same numbering system used by most spreadsheet programs, although some specify incorrectly that February 29, 1900 existed, and thus set January 1, 1900 to 1.0.

VT_DATE | VT_BYREF

A reference to a date was passed. A pointer to the value is in pdate.

VT_DECIMAL | VT_BYREF

A reference to a decimal value was passed. A pointer to the value is in pdecVal.

VT_DISPATCH

A pointer to an object was specified. The pointer is in pdispVal. This object is known only to implement IDispatch. The object can be queried as to whether it supports any other desired interface by calling QueryInterfaceon the object. Objects that do not implement IDispatchshould be passed using VT_UNKNOWN.

VT_DISPATCH | VT_BYREF

A pointer to a pointer to an object was specified. The pointer to the object is stored in the location referred to by ppdispVal.

VT_EMPTY

No value was specified. If an optional argument to an Automation method is left blank, do not pass a VARIANT of type VT_EMPTY. Instead, pass a VARIANT of type VT_ERROR with a value of DISP_E_PARAMNOTFOUND.

VT_EMPTY | VT_BYREF

Not valid.

VT_ERROR

An SCODE was specified. The type of the error is specified in scode. Generally, operations on error values should raise an exception or propagate the error to the return value, as appropriate.

VT_ERROR | VT_BYREF

A reference to an SCODE was passed. A pointer to the value is in pscode .

VT_I1

A 1-byte character value is stored in cVal.

VT_I1 | VT_BYREF

A reference to a 1-byte character was passed. A pointer the value is in pcVal.

VT_I2

A 2-byte integer value is stored in iVal.

VT_I2 | VT_BYREF

A reference to a 2-byte integer was passed. A pointer to the value is in piVal.

VT_I4

A 4-byte integer value is stored in lVal.

VT_I4 | VT_BYREF

A reference to a 4-byte integer was passed. A pointer to the value is in plVal.

VT_INT

An integer value is stored in intVal.

VT_INT | VT_BYREF

A reference to an integer value was passed. A pointer to the value is in pintVal.

VT_NULL

A propagating null value was specified. (This should not be confused with the null pointer.) The null value is used for tri-state logic, as with SQL.

VT_NULL | VT_BYREF

Not valid.

VT_R4

An IEEE 4-byte real value is stored in fltVal.

VT_R4 | VT_BYREF

A reference to an IEEE 4-byte real value was passed. A pointer to the value is in pfltVal.

VT_R8

An 8-byte IEEE real value is stored in dblVal.

VT_R8 | VT_BYREF

A reference to an 8-byte IEEE real value was passed. A pointer to its value is in pdblVal.

VT_UI1

An unsigned 1-byte character is stored in bVal.

VT_UI1 | VT_BYREF

A reference to an unsigned 1-byte character was passed. A pointer to the value is in pbVal.

VT_UI2

An unsigned 2-byte integer value is stored in uiVal.

VT_UI2 | VT_BYREF

A reference to an unsigned 2-byte integer was passed. A pointer to the value is in puiVal.

VT_UI4

An unsigned 4-byte integer value is stored in ulVal.

VT_UI4 | VT_BYREF

A reference to an unsigned 4-byte integer was passed. A pointer to the value is in pulVal.

VT_UINT

An unsigned integer value is stored in uintVal.

VT_UINT | VT_BYREF

A reference to an unsigned integer value was passed. A pointer to the value is in puintVal.

VT_UNKNOWN

A pointer to an object that implements the IUnknowninterface is passed in punkVal.

VT_UNKNOWN | VT_BYREF

A pointer to the IUnknowninterface is passed in ppunkVal. The pointer to the interface is stored in the location referred to by ppunkVal.

VT_VARIANT

Invalid. VARIANTARGs must be passed by reference.

VT_VARIANT | VT_BYREF

A pointer to another VARIANTARG is passed in pvarVal. This referenced VARIANTARG will never have the VT_BYREF bit set in vt, so only one level of indirection can ever be present. This value can be used to support languages that allow functions to change the types of variables passed by reference

Requirements

Header oaidl.h
Windows Embedded CE Windows CE 2.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also