STL string to _bstr_t conversion

[Sandeep Kulkarni]

hi i have an STL string object, which has a NULL char in the MIDDLE. For ex: #include using namespace std; .... string str = "abcdefghijklmnopqrstuvwxyz"; str[11] = 0; // str.size() still equals 26 Now i want to convert this string to _bstr_t object, retaining the NULL char and the chars after that. I tried this: _bstr_t bstr = str.c_str(); But only first 11 chars are being copied(till NULL char). Pls help TIA

[ian mariano]

Just replace all '\0' characters in your std::string with some token character which you can convert back once it's a BSTR. Remember BSTRings are 2 bytes wide in Unicode, so NULL is 0x0000.

Ian Mariano - http://www.ian-space.com/
"We are all wave equations in the information matrix of the universe" - me

[Michael Dunn]

basic_string, by definition, does not allow embedded 0 characters. When you stick a 0 in yourself, you're breaking the semantics of basic_string, so anything after that is not guaranteed to work. You'll need to copy the string manually. --Mike-- Personal stuff:: Ericahist | Homepage Shareware stuff:: 1ClickPicGrabber | RightClick-Encrypt CP stuff:: CP SearchBar v2.0.2 | C++ Forum FAQ ---- If my rhyme was a drug, I'd sell it by the gram.

[Nemanja Trifunovic]

Michael Dunn wrote: basic_string, by definition, does not allow embedded 0 characters. Where did you find this information? AFAIK, the C++ standard does not mention this, and the only function that would be affected by embedded 0 characters is c_str()

[Michael Dunn]

hmm... That was just one of those things I saw in passing and it happened to stick in my memory. Of course, I can't find it now. :( So I could be wrong, don't quote me (well, you already did... don't quote me elsewhere ;) ) The closest I can find is this:

basic_string::c_str const E *c_str() const; The member function returns a pointer to a nonmodifiable C string constructed by adding a terminating null element (E(0)) to the controlled sequence. Calling any non-const member function for *this can invalidate the pointer.

That's one aspect that treats E(0) as special, E(0) being '\0' for character strings. Since the caller of c_str() can look for E(0) to mark the end of the returned string, an E(0) in the middle of the string also looks like the end. --Mike-- Personal stuff:: Ericahist | Homepage Shareware stuff:: 1ClickPicGrabber | RightClick-Encrypt CP stuff:: CP SearchBar v2.0.2 | C++ Forum FAQ ---- Kosh reminded me of some of the prima-donna programmers I've worked with. Knew everything but when you asked them a question; never gave you a straight answer.   -- Michael P. Butler in the Lounge

[Nemanja Trifunovic]

Yep, embedded zeros can screw c_str. However, I made this little experiment:

char buffer\[\] = {'h','e','l','l','o', 0, 'w', 'o', 'r', 'l', 'd'};
string s (buffer, sizeof(buffer));
cout << s << " length = " << s.length()<< endl;

And the output (VC 7.1) is:

hello world length = 11

[Paul Ranson]

The tidiest way would be to use ATL's CComBSTR rather than _bstr_t. using namespace std; .... string str = "abcdefghijklmnopqrstuvwxyz"; str[11] = 0; // str.size() still equals 26 CComBSTR bstr ( str.data (), str.size ()) ; Paul