variadic.c

C Primer Plus(第五版)中文版源码,I hope it will help you much

// variadic.c -- variadic macros
#include <stdio.h>
#include <math.h>
#define PR(X, ...) printf("Message " #X ": " __VA_ARGS__)

int main(void)
{
    double x = 48;
    double y;
  
    y = sqrt(x);
    PR(1, "x = %g\n", x);
    PR(2, "x = %.2f, y = %.4f\n", x, y);
   
    return 0;
}