BSTR, _bstr_t and CString, char * conversion

about BSTR, _bstr_t details"_bstr_t and _variant_t" .

CString turn BSTR

BSTR BSTR;

CString strSQL; BSTR = Strsql.allocsysstring ();

...   SysFreeString (Bstrtext); Use out of release

Note: After use, you must use SysFreeString to release ...
BSTR turn CString

BSTR BSTR =:: SysAllocString (L "Test");

CString strSQL; Strsql.empty (); strSQL = (LPCSTR) BSTR;

Or

BSTR BSTR =:: SysAllocString (L "Test");

CString Str (BSTR); CString turn _bstr_t

_bstr_t BSTR;

CString strSQL; BSTR = (_bstr_t) strSQL;

_bstr_t Turn CString

_bstr_t BSTR;

CString strSQL; strSQL = (LPCSTR) BSTR;
BSTR converted into char*
method One, using Convertbstrtostring

BSTR Bstrtext =:: SysAllocString (L "Test");   char * lpszText2 = _com_util:: convertbstrtostring (Bstrtext);   SysFreeString (Bstrtext); Use out of release
delete [] lpszText2;
method Two, using the _bstr_t assignment operator overload

_bstr_t B = bstrtext; char * lpszText2 = b;

char* converted into BSTR
method One, using API functions such as SysAllocString

BSTR Bstrtext =:: SysAllocString (L "Test");   BSTR Bstrtext =:: SysAllocStringLen (L "Test", 4); BSTR Bstrtext =:: SysAllocStringByteLen ("Test", 4);

method Two, using COleVariant or _variant_t

COleVariant Strvar ("This is a Test");  _variant_t Strvar ("This is a Test"); BSTR bstrtext = Strvar.bstrval;

method Three, using _bstr_t, this is one of the easiest ways

BSTR Bstrtext = _bstr_t ("This is a Test"); Method four, using CComBSTR

BSTR Bstrtext = CComBSTR ("This is a Test"); or

CComBSTR BSTR ("This is a Test"); BSTR Bstrtext = BSTR. M_STR;

Method Five, using Convertstringtobstr

char * lpsztext = "Test"; BSTR Bstrtext = _com_util:: Convertstringtobstr (Lpsztext);