可变宏展开
ex. 用法
#define log_pet(level, dlv, format, args ...) \
do { \
if (log_level >= level) \
syslog(dlv, "<%s:%d:%s> " format, __FILE__, __LINE__, __FUNCTION__, ##args); \
} while (0)
或
#define log_pet(level, dlv, format, ...) \
do { \
if (log_level >= level) \
syslog(dlv, "<%s:%d:%s> " format, __FILE__, __LINE__, __FUNCTION__, ##__VA_ARGS__); \
} while (0)
