convert BSTR to wstring

Question

How to convert a char[256] to wstring?

update. here is my current code:

char testDest[256];
char *p= _com_util::ConvertBSTRToString(url->bstrVal);

for (int i = 0; i <= strlen(p); i++)
{
  testDest[i] = p[i];   
}

// need to convert testDest to wstring to I can pass it to this below function...

writeToFile(testDestwstring);

Answer 1

MultiByteToWideChar will return a UTF-16 string. You need to specify the source codepage.

Answer 2

If your input is BSTR (as it seems to be) the data is already Unicode and you can just cast this directly to wstring as follows. _bstr_t has implicit conversions to both char* and wchar* which avoid the need for manual Win32 code conversion.

if (url->bstrVal)
{
    // true => make a new copy - can avoid this if source 
    // no longer needed, by using false here and avoiding SysFreeString on source

    const _bstr_t wrapper(url->bstrVal, true); 
    std::wstring wstrVal((const _wchar_t*)wrapper);
}

See here for more details on this area of Windows usage. It's easy to mess up the use of the Win32 API in this area - using the BSTR wrapper to do this avoids both data copy (if used judiciously) and code complexity.