alternative printf ... multible arguements

jnusa · 12-13-2004, 08:38 AM

Is there anyway to make a function prototype to take multible parameters. I'm trying to make an alternative printf, that besides formating the content, always displays the PID

e.g.

syntax

Code:

...
printj("\nHello %s. Current date is %d.", name, date);

output:

...
PID: 17966 - Hello Jay. Current date is 121304

But it must not be limited to 2 arguments. It should also take 0 or 50 arguments.
Any infomation will be greatly appriciated.

Regards jnusa

bigearsbilly · 12-13-2004, 08:43 AM

man 'stdarg'

Quote:

NAME
stdarg - handle variable argument list

SYNOPSIS
#include <stdarg.h>
va_list pvar;

void va_start(va_list pvar, void parmN);

(type *) va_arg(va_list pvar, type);

void va_copy(va_list dest, va_list src);

void va_end(va_list pvar);

DESCRIPTION
This set of macros allows portable procedures that accept
variable numbers of arguments of variable types to be writ-
ten. Routines that have variable argument lists (such as
printf) but do not use stdarg are inherently non-portable,
as different machines use different argument-passing conven-
tions.

va_list is a type defined for the variable used to traverse
the list.

The va_start() macro is invoked before any access to the
unnamed arguments and initializes pvar for subsequent use by
va_arg() and va_end(). The parameter parmN is the identifier
of the rightmost parameter in the variable parameter list in
the function definition (the one just before the , ...). If
this parameter is declared with the register storage class
or with a function or array type, or with a type that is not
compatible with the type that results after application of
the default argument promotions, the behavior is undefined.

The parameter parmN is required under strict ANSI C compila-
tion. In other compilation modes, parmN need not be supplied
and the second parameter to the va_start() macro can be left
empty (for example, va_start(pvar, )

. This allows for rou-
tines that contain no parameters before the ... in the vari-
able parameter list.

bigearsbilly · 12-13-2004, 08:49 AM

sorry.
yes the prototype is I believe

Code:

int func ( int argc, char **argv, ... )

jnusa · 12-13-2004, 08:51 AM

Ahh... very much like main's argumentlist. Hmm... I'll try to fool around with it.
Appriciate the fast reply.

mayur · 12-14-2004, 06:22 AM

#define MSG(string, args...) { \
printf(string, ##args); }else

int main(void)
{
int total=0, i=0;

for (i=0;i<10;i++){
total+=i;
/* you can also use __FUNCTION__, __LINE__ */
MSG("%s : Total = %d i= %d \n",__FILE__, total, i);
}
}