What's the meaning of BSTR, LPCOLESTR, and others?
winapi
Solution
LPTSTR and LPWSTR and similar defines are really just defines. BSTR and LPOLESTR have special meanings - they indicate the the string pointed to is allocated in a special way.
String pointed to by BSTR must be allocated with SysAllocString() family functions. String pointed to by LPOLESTR is usually to be allocated with CoTaskMemAlloc() (this should be looked up in the documentation to the COM call accepting/returning it).
If allocation/deallocation requirements for strings pointed to by BSTR and LPOLESTR are violated the program can run into undefined behaviour.
Problem
What's the meaning of BSTR, LPCOLESTR, LPCWSTR, LPTSTR, LPCWCHAR, and many others if they're all just a bunch of defines that resolve to wchar_t anyway?