BSTR and char*

[cppshishu]

Dear friends, What is the difference between BSTR and char*. I am writing a COM dll. It has an API which accepts a string (like patient name). Which datatype should be used? BSTR or char*? Please advice me. Thanks in advance Shihab

[CPallini]

Loosely speaking, BSTR is a strange beast, it is zero-terminated like a standard C-string, but it is prefixed by its length like a Pascal one (dont' worry about that, there are API like SysAllocString, or even classes, like _bstr_t, that do the job for you). That stated, BSTR is used for automation, so, if you have to interact with automation clients (for instance, scripting languages) then you have to use BSTR (BTW your server also needs to implement a dual interface...). On the other hand, if your client is a standard Window application, written in C/C++, you can go also with char * (also Visual Basic code will be able to access you component, in a way similar to the one used to access Win32 API functionalities). Hope that helps. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.

[cppshishu]

thank u