Data Type Conversion APIs

The files Oleaut32.dll (for 32-bit systems) and Ole2disp.dll (for 16-bit systems) provide the following low-level functions for converting variant data types. Higher-level variant manipulation functions (such as VariantChangeType) use these functions, but they can also be called directly.

Convert to type	From type	Function
unsigned char	unsigned char	None
	short	VarUI1FromI2(sIn, pbOut)
	long	VarUI1FromI4(lIn, pbOut)
	float	VarUI1FromR4(fltIn, pbOut)
	double	VarUI1FromR8(dblIn, pbOut)
	CURRENCY	VarUI1FromCy(cyIn, pbOut)
	DATE	VarUI1FromDate(dateIn, pbOut)
	OLECHAR FAR*	VarUI1FromStr(strIn, lcid, dwFlags, pbOut)
	IDispatch FAR*	VarUI1FromDisp(pdispIn, lcid, pbOut)
	BOOL	VarUI1FromBool(boolIn, pbOut)
short	unsigned char	VarI2FromUI1(bIn, psOut)
	short	None
	long	VarI2FromI4(lIn, psOut)
	float	VarI2FromR4(fltIn, psOut)
	double	VarI2FromR8(dblIn, psOut)
	CURRENCY	VarI2FromCy(cyIn, psOut)
	DATE	VarI2FromDate(dateIn, psOut)
	OLECHAR FAR*	VarI2FromStr(strIn, lcid, dwFlags, psOut)
	IDispatch FAR*	VarI2FromDisp(pdispIn, lcid, psOut)
	BOOL	VarI2FromBool(boolIn, psOut)
long	unsigned char	VarI4FromUI1(bIn, plOut)
	short	VarI4FromI2(sIn, plOut)
	long	None
	float	VarI4FromR4(fltIn, plOut)
	double	VarI4FromR8(dblIn, plOut)
	CURRENCY	VarI4FromCy(cyIn, plOut)
	DATE	VarI4FromDate(dateIn, plOut)
	OLECHAR FAR*	VarI4FromStr(strIn, lcid, dwFlags, plOut)
	IDispatch FAR*	VarI4FromDisp(pdispIn, lcid, plOut)
	BOOL	VarI4FromBool(boolIn, plOut)
float	unsigned char	VarR4FromUI1(bIn, pfltOut)
	short	VarR4FromI2(sIn, pfltOut)
	long	VarR4FromI4(lIn, pfltOut)
	float	None
	double	VarR4FromR8(dblIn, pfltOut)
	CURRENCY	VarR4FromCy(cyIn, pfltOut)
	DATE	VarR4FromDate(dateIn, pfltOut)
	OLECHAR FAR*	VarR4FromStr(strIn, lcid, dwFlags, pfltOut)
	IDispatch FAR*	VarR4FromDisp(pdispIn, lcid, pfltOut)
	BOOL	VarR4FromBool(boolIn, pfltOut)
double	unsigned char	VarR8FromUI1(bIn, pdblOut)
	short	VarR8FromI2(sIn, pdblOut)
	long	VarR8FromI4(lIn, pdblOut)
	float	VarR8FromR4(fltIn, pdblOut)
	double	None
	CURRENCY	VarR8FromCy(cyIn, pdblOut)
	DATE	VarR8FromDate(dateIn, pdblOut)
	OLECHAR FAR*	VarR8FromStr(strIn, lcid, dwFlags, pdblOut)
	IDispatch FAR*	VarR8FromDisp(pdispIn, lcid, pdblOut)
	BOOL	VarR8FromBool(boolIn, pdblOut)
DATE	unsigned char	VarDateFromUI1(bIn, pdateOut)
	short	VarDateFromI2(sIn, pdateOut)
	long	VarDateFromI4(lIn, pdateOut)
	float	VarDateFromR4(fltIn, pdateOut)
	double	VarDateFromR8(dblIn, pdateOut)
	CURRENCY	VarDateFromCy(cyIn, pdateOut)
	DATE	None
	OLECHAR FAR*	VarDateFromStr(strIn, lcid, dwFlags, pdateOut)
	IDispatch FAR*	VarDateFromDisp(pdispIn, lcid, pdateOut)
	BOOL	VarDateFromBool(boolIn, pdateOut)
CURRENCY	unsigned char	VarCyFromUI1(bIn, pcyOut)
	short	VarCyFromI2(sIn, pcyOut)
	long	VarCyFromI4(lIn, pcyOut)
	float	VarCyFromR4(fltIn, pcyOut)
	double	VarCyFromR8(dblIn, pcyOut)
	CURRENCY	None
	DATE	VarCyFromDate(dateIn, pcyOut)
	OLECHAR FAR*	VarCyFromStr(strIn, lcid, dwFlags, pcyOut)
	IDispatch FAR*	VarCyFromDisp(pdispIn, lcid, pcyOut)
	BOOL	VarCyFromBool(boolIn, pcyOut)
BSTR	unsigned char	VarBstrFromUI1(bVal, lcid, dwFlags, pbstrOut)
	short	VarBstrFromI2(iVal, lcid, dwFlags, pbstrOut)
	long	VarBstrFromI4(lIn, lcid, dwFlags, pbstrOut)
	float	VarBstrFromR4(fltIn, lcid, dwFlags, pbstrOut)
	double	VarBstrFromR8(dblIn, lcid, dwFlags, pbstrOut)
	CURRENCY	VarBstrFromCy(cyIn, lcid, dwFlags, pbstrOut)
	DATE	VarBstrFromDate(dateIn, lcid, dwFlags, pbstrOut)
	OLECHAR FAR*	None
	IDispatch FAR*	VarBstrFromDisp(pdispIn, lcid, dwFlags, pbstrOut)
	BOOL	VarBstrFromBool(boolIn, lcid, dwFlags, pbstrOut)
BOOL	unsigned char	VarBoolFromUI1(bIn, pboolOut)
	short	VarBoolFromI2(sIn, pboolOut)
	long	VarBoolFromI4(lIn, pboolOut)
	float	VarBoolFromR4(fltIn, pboolOut)
	double	VarBoolFromR8(dblIn, pboolOut)
	CURRENCY	VarBoolFromCy(cyIn, pboolOut)
	DATE	VarBoolFromDate(dateIn, pboolOut)
	OLECHAR FAR*	VarBoolFromStr(strIn, lcid, dwFlags, pboolOut)
	IDispatch FAR*	VarBoolFromDisp(pdispIn, lcid, pboolOut)
	BOOL	None

Parameters

bIn, sIn, lIn, fltIn, dblIn, cyIn, dateIn, strIn, pdispIn, boolIn

The value to coerce. These parameters have the following data types:

Parameter	Data type
bIn	unsigned char
sIn	short
lIn	long
fltIn	float
dblIn	double
cyIn	CURRENCY
dateIn	DATE
strIn	OLECHAR FAR*
pdispIn	IDispatch FAR*
boolIn	BOOL

lcid

For conversions from string and VT_DISPATCH input, the LCID to use for the conversion. For a list of LCIDs, see "Supporting Multiple National Languages" in Chapter 2, "Exposing Automation Objects."

dwFlags

One or more of the following flags:

Flag	Description
LOCALE_NOUSEROVERRIDE	Uses the system default locale settings, rather than custom locale settings.
VAR_TIMEVALUEONLY	Omits the date portion of a VT_DATE and returns only the time. Applies to conversions to or from dates.
VAR_DATEVALUEONLY	Omits the time portion of a VT_DATE and returns only the time. Applies to conversions to or from dates.

pbOut, psOut, plOut, pfltOut, pdblOut, pcyOut, pstrOut, pdispOut, pboolOut

A pointer to the coerced value. These parameters have the following data types:

Parameter	Data type
pbOut	unsigned char
psOut	short
plOut	long
pfltOut	float
pdblOut	double
pcyOut	CURRENCY
pdateOut	DATE
pstrOut	OLECHAR FAR*
pdispOut	IDispatch FAR*
pboolOut	BOOL

Return Value

The return value obtained from the returned HRESULT is one of the following.

Return value	Meaning
S_OK	Success.
DISP_E_BADVARTYPE	The input parameter is not a valid type of variant.
DISP_E_OVERFLOW	The data pointed to by the output parameter does not fit in the destination type.
DISP_E_TYPEMISMATCH	The argument could not be coerced to the specified type.
E_INVALIDARG	One of the arguments is invalid.
E_OUTOFMEMORY	Memory could not be allocated for the conversion.