define 变参__VA_ARGS__,"#","##"的使用

摘自[C 语言 define 变参__VA_ARGS__使用](https://www.cnblogs.com/langzou/p/6674528.html) #define中的"\#" "\#\#" - "\#":宏展开时候替换#后面紧跟的变量 - "\#\#":连接"##"前后的内容(变量) 例子: ```C #include "stdio.h" #define LOG_TYPE1(format, ...) do{ \ printf(format, __VA_ARGS__); \ } while(0) #define LOG_TYPE2(format, args...) do{ \ printf(format, args); \ } while(0) #define LOG_TYPE3(format, ...) do{ \ printf(format, ##__VA_ARGS__); \ } while(0) #define LOG_TYPE4(format, args...) do{ \ printf(format, ##args); \ } while(0) #define LOG(x) printf("LOG "#x" %d \n", x); int value = 10; int main() { //LOG_TYPE1("hello %d \n"); error LOG_TYPE1("hello %d \n", 1); //LOG_TYPE2("hello \n"); error LOG_TYPE2("hello %d \n", 2); LOG_TYPE3("hello 3\n"); LOG_TYPE3("hello %d\n", 3); LOG_TYPE4("hello 4\n"); LOG_TYPE4("hello %d\n", 4); LOG(10); LOG(value); return 0; } ``` 结果: ```LOG hello world. hello 1 hello 2 hello 3 hello 3 hello 4 hello 4 LOG 10 10 LOG value 10 ```