使用 __VA_ARGS__ 调用 printf 在 function 中不起作用，但在宏中起作用

Question

The following macro works:

#define DEBUG(msg, ...) printf(msg, __VA_ARGS__)

But when I add my own function, it says error: '__VA_ARGS__' was not declared in this scope . My code:

void Debug(const char* msg, ...) {
    printf(msg, __VA_ARGS__);
}

#define DEBUG(msg, ...) Debug(msg, __VA_ARGS__)

Is there any way to do so?

Answer 1

Variadic parameter pack is your friend in this case:

template< typename ... Args >
void Debug( const char * msg, Args ... args ) {
    printf( msg, args ... );
}

Answer 2

__VA_ARGS__ simply does not exist outside of a variadic macro. For what you are attempting, use vprintf() instead of printf() , eg:

void Debug(const char* msg, ...) {
    va_list args;
    va_start(args, msg);
    vprintf(msg, args);
    va_end(args);
}

#define DEBUG(msg, ...) Debug(msg, __VA_ARGS__)