Can the void pointer returned by SafeArrayGetElement function be casted into a C++ type?

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I am writing a class to simplify database query on sql server ce the code I am rewring to suite my purpose is located here

http://msdn.microsoft.com/en-us/library/windows/desktop/ms675047(v=vs.85).aspx

Can the void pointer returned by SafeArrayGetElement function be casted into a C++ type?

If not can it be casted into an sql datatype?

Posted 7-Feb-14 3:04am

Gbenbam

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Jochen Arndt · Accepted Answer · 2014-02-07T03:50:00

Solution 1

See the _variant_t[^] class and the extractor functions. When the requested type is not identical to the type stored in the variant, the class tries to perform a conversion. Use the vt member of the encapsulated VARIANT type to determine which type is stored.

Posted 7-Feb-14 3:50am

Jochen Arndt

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Gbenbam 7-Feb-14 10:51am

Thanks I really appreciate it.What I gather is that I first have to save o
into a vatiant and cast into any data type I want.But for null terminated string I need to cast to a bstr fitst before casting to char string.

Jochen Arndt 7-Feb-14 11:05am

There is no need to cast:
- The variant type covers all types that may occur in your database
- Access the variable using extractor functions or the VARIANT member that matches the type
- With _bstr_t, use the wchar_t* operator to access the string (note that it is an operator and not a casting)
- Alternatively copy the variant to a CString which suppports them for constructor and assignment

Gbenbam 8-Feb-14 3:12am

I am sorry to border you again on this question.How does one use these accessor functions.My understanding of opetator is limeted to overloading of operators like = + - * % etc.I have always believed that. operators are autimatically invoked when expression involving them are executed.

Could you show me perhaps a one line of code that illustrate how. they are used.
Or is it that I just assign each to the other to initiate. the associated operator.

Gbenbam 8-Feb-14 10:46am

Thanks man I finally get it.All I need do is assigned to the equivalent data type and th appropriate operator is invoked.
For bstr I assign to a wchar_t * type and the appropriate operator is called.

Thanks a million times.

Jochen Arndt 9-Feb-14 4:53am

Fine that you got it and my answer helped you.
Sorry for the late reply, but I was busy yesterday.