Platform SDK: Automation VariantChangeType Converts a variant from one type to another.HRESULT VariantChangeType( VARIANTARG * pvargDest, VARIANTARG * pvarSrc, unsigned short wFlags, VARTYPE vt ); Parameters pvargDest A pointer to the coerced argument. If this is the same as pvarSrc, the variant will be converted in place. pvarSrc A pointer to the argument to be coerced. wFlags Flags that control the coercion. Acceptable values are: VARIANT_NOVALUEPROP. Prevents the function from attempting to coerce an object to a fundamental type by getting the Value property. Applications should set this flag only if necessary, because it makes their behavior inconsistent with other applications. VARIANT_ALPHABOOL. Converts a VT_BOOL value to a string containing either "True" or "False". VARIANT_NOUSEROVERRIDE. For conversions to or from VT_BSTR, passes LOCALE_NOUSEROVERRIDE to the core coercion routines. VARIANT_LOCALBOOL. For conversions from VT_BOOL to VT_BSTR and back, uses the language specified by the locale in use on the local computer. vt The type to coerce to. If the return code is S_OK, the vt field of the *pvargDest is always the same as this value. Return Value The return value obtained from the returned HRESULT is one of the following.Value Meaning S_OK Success. DISP_E_BADVARTYPE The variant type vt is not a valid type of variant. DISP_E_OVERFLOW The data pointed to by pvarSrc 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. Comments The VariantChangeType function handles coercions between the fundamental types (including numeric-to-string and string-to-numeric coercions). The pvarSrc argument is changed during the conversion process. For example, if the source variant is of type VT_BOOL and the destination is of type VT_UINT, the pvarSrc argument is first converted to VT_I2 and then the conversion proceeds. A variant that has VT_BYREF set is coerced to a value by obtaining the referenced value. An object is coerced to a value by invoking the object's Value property (DISPID_VALUE). Typically, the implementor of IDispatch::Invoke determines which member is being accessed, and then calls VariantChangeType to get the value of one or more arguments. For example, if the IDispatch call specifies a SetTitle member that takes one string argument, the implementor would call VariantChangeType to attempt to coerce the argument to VT_BSTR. If VariantChangeType does not return an error, the argument could then be obtained directly from the bstrVal field of the VARIANTARG. If VariantChangeType returns DISP_E_TYPEMISMATCH, the implementor would set *puArgErr to 0 (indicating the argument in error) and return DISP_E_TYPEMISMATCH from IDispatch::Invoke.Arrays of one type cannot be converted to arrays of another type with this function.Note The type of a VARIANTARG should not be changed in the rgvarg array in place.Requirements Windows NT/2000: Requires Windows NT 3.1 or later. Windows 95/98: Requires Windows 95 or later. Header: Declared in oleauto.h. Library: Use oleaut32.lib.See Also VariantChangeTypeExPlatform SDK Release: November 2001 What did you think of this topic? Let us know. Order a Platform SDK CD Online (U.S/Canada) (International) Requirements Windows NT/2000: Requires Windows NT 3.1 or later. Windows 95/98: Requires Windows 95 or later. Header: Declared in oleauto.h. Library: Use oleaut32.lib. See Also VariantChangeTypeEx
CString str = var.bstrVal
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char *p;
p=(char*)your_variant_t;
Platform SDK: Automation
VariantChangeType
Converts a variant from one type to another.HRESULT VariantChangeType(
VARIANTARG * pvargDest,
VARIANTARG * pvarSrc,
unsigned short wFlags,
VARTYPE vt
);
Parameters
pvargDest
A pointer to the coerced argument. If this is the same as pvarSrc, the variant will be converted in place.
pvarSrc
A pointer to the argument to be coerced.
wFlags
Flags that control the coercion. Acceptable values are:
VARIANT_NOVALUEPROP. Prevents the function from attempting to coerce an object to a fundamental type by getting the Value property. Applications should set this flag only if necessary, because it makes their behavior inconsistent with other applications.
VARIANT_ALPHABOOL. Converts a VT_BOOL value to a string containing either "True" or "False".
VARIANT_NOUSEROVERRIDE. For conversions to or from VT_BSTR, passes LOCALE_NOUSEROVERRIDE to the core coercion routines.
VARIANT_LOCALBOOL. For conversions from VT_BOOL to VT_BSTR and back, uses the language specified by the locale in use on the local computer.
vt
The type to coerce to. If the return code is S_OK, the vt field of the *pvargDest is always the same as this value.
Return Value
The return value obtained from the returned HRESULT is one of the following.Value Meaning
S_OK Success.
DISP_E_BADVARTYPE The variant type vt is not a valid type of variant.
DISP_E_OVERFLOW The data pointed to by pvarSrc 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. Comments
The VariantChangeType function handles coercions between the fundamental types (including numeric-to-string and string-to-numeric coercions). The pvarSrc argument is changed during the conversion process. For example, if the source variant is of type VT_BOOL and the destination is of type VT_UINT, the pvarSrc argument is first converted to VT_I2 and then the conversion proceeds. A variant that has VT_BYREF set is coerced to a value by obtaining the referenced value. An object is coerced to a value by invoking the object's Value property (DISPID_VALUE). Typically, the implementor of IDispatch::Invoke determines which member is being accessed, and then calls VariantChangeType to get the value of one or more arguments. For example, if the IDispatch call specifies a SetTitle member that takes one string argument, the implementor would call VariantChangeType to attempt to coerce the argument to VT_BSTR. If VariantChangeType does not return an error, the argument could then be obtained directly from the bstrVal field of the VARIANTARG. If VariantChangeType returns DISP_E_TYPEMISMATCH, the implementor would set *puArgErr to 0 (indicating the argument in error) and return DISP_E_TYPEMISMATCH from IDispatch::Invoke.Arrays of one type cannot be converted to arrays of another type with this function.Note The type of a VARIANTARG should not be changed in the rgvarg array in place.Requirements
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in oleauto.h.
Library: Use oleaut32.lib.See Also
VariantChangeTypeExPlatform SDK Release: November 2001 What did you think of this topic?
Let us know. Order a Platform SDK CD Online
(U.S/Canada) (International) Requirements
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in oleauto.h.
Library: Use oleaut32.lib.
See Also
VariantChangeTypeEx