variadic macros
// variadic_macros.cpp
#include <stdio.h>
#define EMPTY
#define CHECK1(x, ...) if (!(x)) { printf(__VA_ARGS__); }
#define CHECK2(x, ...) if ((x)) { printf(__VA_ARGS__); }
#define CHECK3(...) { printf(__VA_ARGS__); }
#define MACRO(s, ...) printf(s, __VA_ARGS__)
int main() {
CHECK1(0, "here %s %s %s", "are", "some", "varargs1(1)n");
CHECK1(1, "here %s %s %s", "are", "some", "varargs1(2)n"); // won't print
CHECK2(0, "here %s %s %s", "are", "some", "varargs2(3)n"); // won't print
CHECK2(1, "here %s %s %s", "are", "some", "varargs2(4)n");
// always invokes printf in the macro
CHECK3("here %s %s %s", "are", "some", "varargs3(5)n");
MACRO("hello, worldn");
MACRO("errorn", EMPTY); // would cause error C2059, except VC++
// suppresses the trailing comma
}