Re: Converting a LPSTR* to BSTR* and back again.

"glennanthonyb" <glenn.csharp@yahoo.co.uk> ha scritto nel messaggio
news:OOitmM84HHA.484@TK2MSFTNGP06.phx.gbl...


I did not ask for it... and this information does not help me.

However, you may consider the following code to convert BSTR <-> ANSI (I
embedded the conversion code into a couple of functions, and did a test in
WinMain; you should review and better test the code; however, it seems to
work OK):

<code>
//=========================================================
// Converstion of strings BSTR <-> ANSI
// By Giovanni Dicanio
// (2007, August)
//=========================================================
#include <Windows.h>
#include <atlbase.h>
#include <atlconv.h>
#include <strsafe.h>

//---------------------------------------------------------
// Convert an ANSI string to a BSTR
//---------------------------------------------------------
void StringAnsiToBstr(
   IN const char * sz,
   OUT BSTR * pbstr
)
{
   ATLASSERT( sz != NULL );
   ATLASSERT( pbstr != NULL );

   // Build a CComBSTR object assigning the input
   // ANSI string (the constructor converts from
   // ANSI to BSTR)
   CComBSTR bstr( sz );

   // Copy to destination BSTR parameter,
   // releasing the BSTR
   *pbstr = bstr.Detach();
}

//---------------------------------------------------------
// Convert a BSTR to ANSI.
// The caller must provide memory buffer for ANSI,
// and the buffer size (in char's)
//---------------------------------------------------------
void StringBstrToAnsi(
   IN BSTR * pbstr,
   OUT char * sz,
   IN size_t cch
)
{
   ATLASSERT( pbstr != NULL );
   ATLASSERT( *pbstr != NULL );
   ATLASSERT( sz != NULL );
   ATLASSERT( cch != 0 );

   // Build an helper CComBSTR object with the input string
   CComBSTR bstr( *pbstr );

   // Convert from Unicode to ANSI
   CW2A ansi( bstr );

   // Copy ANSI to destination buffer
   StringCchCopyA( sz, cch, ansi );
}

//---------------------------------------------------------
// *** TEST ***
//---------------------------------------------------------
int CALLBACK WinMain(
   IN HINSTANCE hInstance,
   IN HINSTANCE hPrevInstance,
   IN LPSTR lpCmdLine,
   IN int nShowCmd )
{
   // Source ANSI string
   const char * name = "Bob";

   // Convert from ANSI to BSTR
   BSTR bstr;
   StringAnsiToBstr( name, &bstr );

   // Display the BSTR string
   MessageBoxW( NULL, bstr, L"The BSTR string is: ", MB_OK );

   // Convert from BSTR back to ANSI
   static const int ansiCch = 100;
   char ansi[ ansiCch ];
   ZeroMemory( ansi, sizeof(ansi) );
   StringBstrToAnsi( &bstr, ansi, ansiCch );

   // Display ANSI string
   MessageBoxA( NULL, ansi, "The ANSI string is: ", MB_OK );

   // Manually release the bstr
   SysFreeString( bstr );
   bstr = NULL;

   return 0;
}

</code>

Giovanni