How to convert *string to _bstr_t and *BSTR

agarunk

Hi, I'm creating dll using VS2005 ATL project. I'm using third party SDK API's which extracts data into a *string variable. Now I'm facing problem with converting the *string to _bstr_t and *BSTR. Please guide me whether is it possible to convert *string to _bstr_t and *BSTR, if so how to do it. If possible with a sample piece of code. thanking you, Arun

Lim Bio Liong

Hello agarunk, By "*string", do you mean a pointer to a STL string ? By "*BSTR", do you mean a pointer to a BSTR ? - Bio.

agarunk

Hi Bio, Its "std::string*", i.e., pointer to std string. and yes "BSTR*" is pointer to a BSTR. -Arun

Steve S

Both the _bstr_t wrapper class and BSTR expect the text to be UNICODE, rather than ANSI or MBCS. While _bstr_t can convert from LPCSTR, BSTR on it's own can't. You will need to use the c_str() member function of the std::string to get your LPCSTR in the first place (unlike MFC/ATL/WTL CString class, there's no LPCTSTR operator). Like I say, you can then use this pointer with something like A2W or MultiByteToWideChar.

Steve S Developer for hire

agarunk

Hi Steve, Below is the implementation which I'm using now.... BSTR* TargetBSTR ; string *SourceStr=new string; string StrBuff; const char *CharBuff; StrBuff=*SourceStr; CharBuff=StrBuff.c_str(); *TargetBSTR = _com_util::ConvertStringToBSTR(CharBuff); Is this what you are asking me to do??? It is working fine for me for time being... I would like to know if I'm doing any mistake. Is there any issues with it??? -Arun

Michael Dunn

Check out The Complete Guide to C++ Strings, Part II - String Wrapper Classes[^]

--Mike-- Visual C++ MVP :cool: LINKS~! Ericahist | PimpFish | CP SearchBar v3.0 | C++ Forum FAQ

Zac Howland

Steve S wrote:

Both the _bstr_t wrapper class and BSTR expect the text to be UNICODE, rather than ANSI or MBCS. While _bstr_t can convert from LPCSTR, BSTR on it's own can't.

This isn't completely accurate. _bstr_t has a constructor that takes a const char*. It will do the conversion for you. Basically, if you need to convert std::string* to a _bstr_t* (or even to a BSTR*), here is a simple way to do it:

std::string* pStlString = new string("my stuff");
_bstr_t* pBstrWrapper = new _bstr_t(pStlString->c_str());
BSTR* pBstr = pBstrWrapper->GetAddress();

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac

Zac Howland

agarunk wrote:

BSTR* TargetBSTR ; string *SourceStr=new string; string StrBuff; const char *CharBuff; StrBuff=*SourceStr; CharBuff=StrBuff.c_str(); *TargetBSTR = _com_util::ConvertStringToBSTR(CharBuff);

That is far more code than you need to do for this. See my response below.

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac

Steve S

I sit corrected :) I confess that these days I very rarely use ANSI/MBCS, since I no longer do stuff for Win9x/ME platforms. Lucky me, my end-customers all use W2K or later...

Steve S Developer for hire

Zac Howland

Since I'm in the Linux world at my new job, I'm a bit rusty myself. I do find that using the T-functions (along with classes that can use both char* and wchar_t*) alleviates much of those headaches.

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac