VARIANT and VARIANTARG (Windows Embedded CE 6.0)

项目
01/05/2012

1/6/2010

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

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 VARIANT type cannot have the VT_BYREF bit set.

The vt value 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 pbyrefVal points 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 QueryInterface on the object. Objects that do not implement IDispatch should 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 infltVal.
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 IUnknown interface is passed inpunkVal.
VT_UNKNOWN \| VT_BYREF	A pointer to the IUnknown interface 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

通过

VARIANT and VARIANTARG (Windows Embedded CE 6.0)

Syntax

Members

Remarks

Requirements

See Also

Reference

其他资源