如何将一个_variant_t类型的值转化为一个CString或是char *?

[guanjinke]

我使用（_bstr_t）强制转化时，出现是乱码。

[功名半纸]

COleVariant var = _variant_t
CString str = var.bstrVal


OR

(LPCTSTR)(_bstr_t)vType

[ActiveOne]

简单，直接用(char*)后面加上你的_variant_t变量就好了。如：
char *p;
p=(char*)your_variant_t;

[WQ]

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
VariantChangeTypeEx

Platform SDK Release: November 2001 What did you think of this topic?
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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