// Declare a CComBSTR object. Although the argument is ANSI,
// the constructor converts it into UNICODE.
CComBSTR bstrMyString("Hello World");
// Convert the string into an ANSI string
CW2A szMyString(bstrMyString);
// Display the ANSI string
MessageBoxA(NULL, szMyString, "String Test", MB_OK);   

// The following converts the ANSI string to Unicode
CComBSTR bstr1("Test");
// The following uses a Unicode string at compile time 
CComBSTR bstr2(L"Test");   

// The wrong way to do it
BSTR * MyBadFunction()
{
   // Create the CComBSTR object
   CComBSTR bstrString(L"Hello World");
   // Convert the string to uppercase
   HRESULT hr;
   hr = bstrString.ToUpper();

   // Return a pointer to the BSTR. ** Bad thing to do **
   return &bstrString;
}
// The correct way to do it
HRESULT MyGoodFunction(/*[out]*/ BSTR* bstrStringPtr)
{
   // Create the CComBSTR object
   CComBSTR bstrString(L"Hello World");
   // Convert the string to uppercase
   HRESULT hr;
   hr = bstrString.ToUpper();
   if (hr != S_OK)
       return hr;
   // Return a copy of the string.
   return bstrString.CopyTo(bstrStringPtr);
}

// Declare a CComBSTR object
CComBSTR bstrMyString(L"Hello World");
// Free the string explicitly
::SysFreeString(bstrMyString);
// The string will be freed a second time
// when the CComBSTR object goes out of scope,
// which is invalid.   

// This is not an efficient way to use a CComBSTR object.
CComBSTR bstrMyString;
HRESULT hr;
while (bstrMyString.Length() < 1000)
   hr = bstrMyString.Append(L"*");