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