About String

String String .......

Sample code
CString cs;
BSTR bstr;
WCHAR wsz[81];
CComBSTR cbstr;
char sz[81];
TCHAR tsz[81];
basic_string bs;
_bstr_t _bstr;

USES_CONVERSION;
    
// Convert CString to various types
cs = "String1";
bstr = cs.AllocSysString();   // BSTR    
_tcscpy(tsz, (LPCTSTR)cs);    // LPCTSTR
strcpy(sz, T2A(tsz));       // ANSI string
wcscpy(wsz, bstr);         // wide string
cbstr = bstr;             // CComBSTR via
bs = sz;                // STL string
_bstr = (LPCTSTR) cs;       // _bstr_t via either
                     //   operator=(const char*) or
                     //   operator=(const wchar_t*)
                     //   if _UNICODE is defined.
::SysFreeString(bstr);

// Convert BSTR to various types
bstr = ::SysAllocString(L"String2");
cs = bstr;               // CString via its LPCWSTR ctor
wcscpy(wsz, bstr);         // Unicode
cbstr = bstr;             // CComBSTR via operator=(LPOLESTR)
strcpy(sz, W2A(bstr));       // ANSI string
bs = sz;                // STL string operator=(const T*)
_tcscpy(tsz, W2T(bstr));     // LPTSTR
_bstr = bstr;             // _bstr_t via operator=(const wchar_t*)
::SysFreeString(bstr);

참조링크
http://www.hal-pc.org/%7Eabeld/cppsighal/vcppstrings.htm#Sample
http://www.oreilly.com/catalog/win32api/chapter/ch06.html
http://www.whooper.co.uk/excelvariants.htm