macros question #2

[Andrew Arro]

first of all i would like to thank Alexander Bartolich and Richard
Heathfield for answering my
"macros question" #1

another macros question now:

how could i define a macros with variable number of parameters? i want
to create



void printfatal(char *file, int line, char *format, ...);


so i wanna define a macros wich i could call like

fatal("%d %s", var1, var2);

and which would be preprocessed into

printfatal(__FILE__, __LINE__, "%d %s", var1, var2);

is that possible?

 

[Kevin D. Quitt]

how could i define a macros with variable number of parameters?
fatal("%d %s", var1, var2);
printfatal(__FILE__, __LINE__, "%d %s", var1, var2);

#define fatal( s, ... ) printfatal( __FILE__, __LINE__, __VA_ARGS__ )

Assuming your compiler handles C99.

 

[E. Robert Tisdale]

#define fatal( s, ... ) printfatal( __FILE__, __LINE__, __VA_ARGS__ )

#define fatal( s, ... ) printfatal( __FILE__, __LINE__, s, __VA_ARGS__ )

 

[Andrew Arro]

#define fatal( s, ... ) printfatal( __FILE__, __LINE__, s, __VA_ARGS__ )

thanx guys, actualy the best option i think is

#define fatal(... ) printfatal( __FILE__, __LINE__, __VA_ARGS__ )

this case
fatal("message")

also works

thanx again!

 

[Kevin D. Quitt]

#define fatal( s, ... ) printfatal( __FILE__, __LINE__, __VA_ARGS__ )

^^
I'm not sure where that came from, but it doesn't belong. Sorry.

 

[Dave Thompson]

how could i define a macros with variable number of parameters? i want
to create



void printfatal(char *file, int line, char *format, ...);


so i wanna define a macros wich i could call like

fatal("%d %s", var1, var2);

and which would be preprocessed into

printfatal(__FILE__, __LINE__, "%d %s", var1, var2);

is that possible?

In addition to the answer already given for C99, which isn't yet
widely implemented, you can do almost but not quite the same thing in
GCC even in older versions.

In the absence of either of those, AFAIK the closest you can come is a
pseudoCurrying hack:

#define fatal /*NOT functionlike*/ \
printfileline(__FILE__,__LINE__), printf /* gets "arguments" */
/* or instead of printf other appropriate variadic function */

or
#define fatal printfilelinethenprintf(__FILE__,__LINE__) which is
declared to return a function pointer and actually returns a pointer
to printf or whatever, which then gets invoked the arguments.

- David.Thompson1 at worldnet.att.net