How does it convert _bstr_t to BSTR when passing as an argument?

Question

Taking a simple example:

_bstr_t smartString(L"MyString");

Process(smartString); // takes BSTR.

Initially I thought _bstr_t has a BSTR operator converting from _bstr_t to BSTR, but looking at msdn there is no such operator defined.

How does it work when passign _bstr_t to BSTR parameter or _variant_t to VARIANT?

Answer 1

BSTR is typedefed to be WCHAR* (wtypes.h file) and the latter is typedefed to be wchar_t* (winnt.h file) and _bstr_t has operator wchar_t*() member variable. So the compiler just uses that operator for conversion.