🚀 go-pugleaf

"Mark Guerrieri" <mguerrieri@nospam_cmsgrp.com> wrote in message
news:457da01d@newsgroups.borland.com...

> The first call to ::WideCharToMultiByte to get the size of the buffer
> ALWAYS returns 0 with GetLastError returning 87- "The Parameter
> is Incorrect"

One thing I notice is that you are not taking into account that
WideString::c_bstr() will return a NULL pointer when the Length() is 0.
Unlike AnsiString::c_str(), which returns a non-NULL pointer instead.  The
lpWideCharStr parameter of WideCharToMultiByte() cannot be NULL.

Try this instead:

    int  __fastcall TCCSMsgObjectEx::BuildMessageFromString(const
WideString& cMessage)
    {
        int nSize;

        if( cMessage.Length() > 0 )
        {
            nSize = ::WideCharToMultiByte(CP_ACP, 0, cMessage.c_bstr(),
cMessage.Length(), NULL, 0, NULL, NULL);
            if( nSize <= 0 )
                RaiseLastOSError();
        }
        else
            nSize = 0;

        if( (!FMessageBuffer) || (nSize > (int)FMessageSize) )
        {
            if(FMessageBuffer)
                free(FMessageBuffer);
            if( nSize > 0 )
            {
                FMessageBuffer = (BYTE*) malloc(nSize);
                if( !FMessageBuffer )
                    OutOfMemoryError();
            }
        }
        FMessageSize = nSize;

        if( nSize > 0 )
        {
            nSize = ::WideCharToMultiByte(CP_ACP, 0, cMessage.c_bstr(),
cMessage.Length(), FMessageBuffer, nSize, NULL, NULL);
            if( nSize <= 0 )
                RaiseLastOSError();
        }

        return FMessageSize;
    }

> If I do the following:
>
> AnsiString cValue = AnsiString(wValue);
> BuildMessageFromString(cValue);
>
> then everything works as expected.

As it should be, because the WideString->AnsiString conversion handles the
condition where the WideString may be empty.

> The string stored in wValue may get quite large at times and I would like
> to avoid the overhead of converting to AnsiString first then storing the
> results in the buffer; ::WideCharToMultiByte should just store directly to
> the buffer for me, it can't seem to handle my NULL-infested string...

Yes, it can, as the VCL uses WideCharToMultiByte() internally for its own
conversion.  If the NULL characters were tripping up WideCharToMultiByte()
in general, then the VCL would be effected as well, which is obviously not
the case.  So the more likely cause is that your use of the function is
simply wrong.  Which is evident by the 87 error code.


Gambit