Say you want to wrap a function like printf() (which receives a variable number of arguments) with a macro. This is how to do it:
#define PRINT_DEBUG(fmt, args...) printf("DBG:"fmt, ##args)
That is, declare them as args… and use them with ##args.
Note: The word args has nothing special, you could similarly use somethingelse… and ##somethingelse. Just in case you were wondering 