format specifiers

[ADoozer]

can anyone point me in the direction of a complete list of format specifiers (%s, %d. %f, etc) in c/c++

im trying to find out why a particular string causes a function to crash when using va_start macro with _vsnprintf

basic code...

void CServerDlg::WriteConsoleString(LPCTSTR pMsg, ...)
{
	TCHAR		str[500];
	va_list		marker;
	int			nLen;

	va_start(marker, pMsg);
	_vsnprintf( str, sizeof( str ) - 1, pMsg, marker );
	va_end(marker);

}

any input appreciated

If somethings hard to do, its not worth doing - Homer Simpson

 

[ArkM]

What's a true problem?
This snippet is OK (if your pMsg is a right format string and no errors in _vsnprintf...

 

[xwb]

sizeof(str) - 1 isn't a good idea if you are using unicode. It should be (sizeof(str)/sizeof(str[0]) - 1

Is one of your strings a CString that hasn't been LPCTSTRed?

 

[ADoozer]

hi, this isnt my code, its a snippet from a game server code (aliens vs. predator 2)

im not concerned at the moment with practical programming practices, i just need to find out what is causing a particular string to crash the server app (so i can do a quick patch) but im completely self taught and i only know the basic format specifiers.

example string

"aaaa%1.f%1.f%1.f%1.f%1.f%1.f%x%x%1.f%x%x%1.f%1.f%1.f%1.f%1.f%1.f%x %n"

apparently the call should be :-

WriteConsoleString("%s",UserStr)

but in the code it is called :-

WriteConsoleString( UserStr )

thnxs for any input

If somethings hard to do, its not worth doing - Homer Simpson

 

[ArkM]

If you pass this format string to this WriteConsoleString, you will have unpredicated behaviour because of this format assumed 6 double arguments, then int arg, then double etc...
WriteConsoleString(UserStr) has no any args after format (but _vsnprintf wants them.
It's a rather strange situation.

 

[ADoozer]

unpredicated behaviour

yup thats what im trying to fix.

ive found a temporary fix (which ive been using for several months, [although i only filtered %n]) its easier to filter in the DLL before the CEDIT box sees the formated code.

quick question on format specifiers...

is %1.f the same as %.1f

thnx

If somethings hard to do, its not worth doing - Homer Simpson

 

[ArkM]

%1.f and %.1f are both %f. In this aspect (where are arguments for %f?) they are identical. The last specifier specifies one digit after decimal point - that's all.

No printed arguments in your case: va_list marker pointer refers to a garbage in the program stack (may be NaN etc).