12 octobers patches _vscwprintf( pszFormat, args ); difference!

[Egbert Nierop \(MVP for IIS\)]

Am I the only one?

After having installed the patches as a brave MS citycen :),
this function suddenly returns one less then before or possible
vswprintf assumes the given length including the terminating zero.

[Doug Harrison [MVP]]

On Thu, 13 Oct 2005 11:49:30 +0200, "Egbert Nierop \(MVP for IIS\)"
<eg***********@nospam.invalid> wrote:

Am I the only one?

After having installed the patches as a brave MS citycen :),
this function suddenly returns one less then before or possible
vswprintf assumes the given length including the terminating zero.

Can you demonstrate this in a little console program?

--
Doug Harrison
Visual C++ MVP

[Egbert Nierop \(MVP for IIS\)]

"Doug Harrison [MVP]" <ds*@mvps.org> wrote in message
news:v5********************************@4ax.com...

On Thu, 13 Oct 2005 11:49:30 +0200, "Egbert Nierop \(MVP for IIS\)"
<eg***********@nospam.invalid> wrote:

Am I the only one?

After having installed the patches as a brave MS citycen :),
this function suddenly returns one less then before or possible
vswprintf assumes the given length including the terminating zero.

Can you demonstrate this in a little console program?

ps: I established this bug. It is not windows but VC 8 which behaves
different with VC 7.
I have mailed this to Michael M (Microsoft).
BSTR __cdecl Format(PCWSTR pszFormat, ...) throw()

{

va_list args;

HRESULT hr = S_OK;

BSTR retVal = NULL;
va_start( args, pszFormat );

int len = _vscwprintf( pszFormat, args );

retVal = SysAllocStringLen(NULL, len);

if(retval != NULL)

vswprintf( retVal, (SIZE_T)len, pszFormat, args );

va_end(args);
return retVal;

}
INT main()

{

CoInitialize(NULL);

{

BSTR test = Format(L"%s, %d,%s", L"one", 2, L"three");

wprintf(test); //"output one, 2, thre" <-- BUG this used to have the
correct length in VC 7?

SysFreeString(test);

}

CoUninitialize();

return 0;

}

[Jochen Kalmbach [MVP]]

Hi Egbert!

ps: I established this bug. It is not windows but VC 8 which behaves
different with VC 7.
I have mailed this to Michael M (Microsoft).
BSTR __cdecl Format(PCWSTR pszFormat, ...) throw()
{
va_list args;
HRESULT hr = S_OK;
BSTR retVal = NULL;
va_start( args, pszFormat );
int len = _vscwprintf( pszFormat, args );
retVal = SysAllocStringLen(NULL, len);
if(retval != NULL)
vswprintf( retVal, (SIZE_T)len, pszFormat, args );
va_end(args);
return retVal;
}
If it had worked in VC7(.1) then it was a bug in VC7(.1) and is now
corrected in VC8 :-)

The following line is wrong: int len = _vscwprintf(pszFormat, args);

You should change it to
int len = _vscwprintf(pszFormat, args) + 1;

The reason is:
_vscprintf doesn't count the terminating '\0'!
but vswprintf requires the terminating NUL in in the count.

--
Greetings
Jochen

My blog about Win32 and .NET
http://blog.kalmbachnet.de/

[Egbert Nierop \(MVP for IIS\)]

"Jochen Kalmbach [MVP]" <no********************@holzma.de> wrote in message
news:ue*************@TK2MSFTNGP15.phx.gbl...

Hi Egbert!

ps: I established this bug. It is not windows but VC 8 which behaves
different with VC 7.
I have mailed this to Michael M (Microsoft).
BSTR __cdecl Format(PCWSTR pszFormat, ...) throw()
{
va_list args;
HRESULT hr = S_OK;
BSTR retVal = NULL;
va_start( args, pszFormat );
int len = _vscwprintf( pszFormat, args );
retVal = SysAllocStringLen(NULL, len);
if(retval != NULL)
vswprintf( retVal, (SIZE_T)len, pszFormat, args );
va_end(args);
return retVal;
}

If it had worked in VC7(.1) then it was a bug in VC7(.1) and is now
corrected in VC8 :-)

Great! :<

Counting on bugs helps one to improve his skills :)