样将_variant_转化为vc中的数组

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VARIANT,变体类型,在VC 中是一个可以容纳很多常用类型的超级类型,所以,如果不知道它的里面到底存了些什么数据,对着它就像对着一个从未见过面的朋友一样,不知该怎么交流.在这种情况下,我们可以通过取得VARIANT类型变量的vt值,得以确认:
      enum VARENUM
    { VT_EMPTY = 0,
VT_NULL = 1,
VT_I2 = 2,
VT_I4 = 3,
VT_R4 = 4,
VT_R8 = 5,
VT_CY = 6,
VT_DATE = 7,
VT_BSTR = 8,
VT_DISPATCH = 9,
VT_ERROR = 10,
VT_BOOL = 11,
VT_VARIANT = 12,
VT_UNKNOWN = 13,
VT_DECIMAL = 14,
VT_I1 = 16,
VT_UI1 = 17,
VT_UI2 = 18,
VT_UI4 = 19,
VT_I8 = 20,
VT_UI8 = 21,
VT_INT = 22,
VT_UINT = 23,
VT_VOID = 24,
VT_HRESULT = 25,
VT_PTR = 26,
VT_SAFEARRAY = 27,
VT_CARRAY = 28,
VT_USERDEFINED = 29,
VT_LPSTR = 30,
VT_LPWSTR = 31,
VT_RECORD = 36,
VT_FILETIME = 64,
VT_BLOB = 65,
VT_STREAM = 66,
VT_STORAGE = 67,
VT_STREAMED_OBJECT = 68,
VT_STORED_OBJECT = 69,
VT_BLOB_OBJECT = 70,
VT_CF = 71,
VT_CLSID = 72,
VT_BSTR_BLOB = 0xfff,
VT_VECTOR = 0x1000,
VT_ARRAY = 0x2000,
VT_BYREF = 0x4000,
VT_RESERVED = 0x8000,
VT_ILLEGAL = 0xffff,
VT_ILLEGALMASKED = 0xfff,
VT_TYPEMASK = 0xfff
    };

这个枚举结构里,存着vt值的宏定义,假如m_DataA为VARIANT类型变量,m_DataA .vt = 4,则这个变量里的就是存的一个单精度数据(以上宏在MSDN均可查到所代表的类型),当然,上面的宏可以叠加使用,比如说m_DataA.vt = 8204,转化成十六进制数为0x200C,VT_ARRAY = 0x2000,VT_VARIANT = 12(12的十六进制为:C),变量里存的数据是一个变体数组类型(VT_ARRAY |VT_VARIANT ).

确定类型以后就可以直接读数了,比如:

variant var; //假设这个变量中保存了数组元素
SAFEARRAY* psa = var.parray;
long count = psa->rgsabound->cElements; //判断元素个数
定义buf数组；
for (long i=0; i<count; i++)
{
SafeArrayGetElement(psa,&i,&buf[i]); //buf为你定义的数组
}

你还可以根据 vt 域的不同来建立更通用的转换例程。为此你可能会考虑：

CString VariantToString(VARIANT * va)

{ CString s;

switch(va->vt)

{ /* vt */ case VT_BSTR:

return CString(vaData->bstrVal);

case VT_BSTR | VT_BYREF:

return CString(*vaData->pbstrVal);

case VT_I4:

s.Format(_T(\"%d\"), va->lVal);

return s; case VT_I4 | VT_BYREF:

s.Format(_T(\"%d\"), *va->plVal);

case VT_R8:

s.Format(_T(\"%f\"), va->dblVal);

return s; ... 剩下的类型转换由读者自己完成

default: ASSERT(FALSE);

// unknown VARIANT type (this ASSERT is optional) return CString(\"\"); } /* vt */}